X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=dgit;h=920787457bd271b3aecef6d0eecb8c1f924d9200;hb=fe216b34e36c059be82c18cfe850c729e5c8df21;hp=4587af257532c1c64036651feeb7d8c4d7fd3d85;hpb=75dd5aef7f0d91ce0ac78285cc15843f686f5914;p=dgit.git

diff --git a/dgit b/dgit
index 4587af25..92078745 100755
--- a/dgit
+++ b/dgit
@@ -32,6 +32,7 @@ use Data::Dumper;
 use LWP::UserAgent;
 use Dpkg::Control::Hash;
 use File::Path;
+use File::Spec;
 use File::Temp qw(tempdir);
 use File::Basename;
 use Dpkg::Version;
@@ -102,7 +103,7 @@ our %format_ok = map { $_=>1 } ("1.0","3.0 (native)","3.0 (quilt)");
 
 our $suite_re = '[-+.0-9a-z]+';
 our $cleanmode_re = qr{(?: dpkg-source (?: -d )? (?: ,no-check | ,all-check )?
-                         | git | git-ff
+                     | (?: git | git-ff ) (?: ,always )?
                          | check (?: ,ignores )?
                          | none
                          )}x;
@@ -132,8 +133,8 @@ our (@mergechanges) = qw(mergechanges -f);
 our (@gbp_build) = ('');
 our (@gbp_pq) = ('gbp pq');
 our (@changesopts) = ('');
-our (@pbuilder) = ("sudo -E pbuilder");
-our (@cowbuilder) = ("sudo -E cowbuilder");
+our (@pbuilder) = ("sudo -E pbuilder","--no-source-only-changes");
+our (@cowbuilder) = ("sudo -E cowbuilder","--no-source-only-changes");
 
 our %opts_opt_map = ('dget' => \@dget, # accept for compatibility
 		     'curl' => \@curl,
@@ -164,6 +165,7 @@ our %opts_cfg_insertpos = map {
 } keys %opts_opt_map;
 
 sub parseopts_late_defaults();
+sub quiltify_trees_differ ($$;$$$);
 sub setup_gitattrs(;$);
 sub check_gitattrs($$);
 
@@ -173,7 +175,31 @@ our $keyid;
 autoflush STDOUT 1;
 
 our $supplementary_message = '';
-our $split_brain = 0;
+our $made_split_brain = 0;
+our $do_split_brain = 0;
+
+# Interactions between quilt mode and split brain
+# (currently, split brain only implemented iff
+#  madformat_wantfixup && quiltmode_splitbrain)
+#
+#   source format        sane           `3.0 (quilt)'
+#                                       madformat_wantfixup()
+#
+#   quilt mode                          normal              quiltmode
+#                                       (eg linear)         _splitbrain
+#
+#   ------------      ------------------------------------------------
+#
+#   no split          no q cache        no q cache          forbidden,
+#     brain           PM on master      q fixup on master   prevented
+#   !$do_split_brain                    PM on master
+#
+#   split brain       no q cache        q fixup cached, to dgit view
+#                     PM in dgit view   PM in dgit view
+#
+# PM = pseudomerge to make ff, due to overwrite (or split view)
+# "no q cache" = do not record in cache on build, do not check cache
+# `3.0 (quilt)' with --quilt=nocheck is treated as sane format
 
 END {
     local ($@, $?);
@@ -257,7 +283,7 @@ sub forceing ($) {
 }
 
 sub no_such_package () {
-    print STDERR f_ "%s: package %s does not exist in suite %s\n",
+    print STDERR f_ "%s: source package %s does not exist in suite %s\n",
 	$us, $package, $isuite;
     finish 4;
 }
@@ -396,7 +422,9 @@ sub branch_is_gdr ($) {
 	    return 0;
 	}
 	if ($tip_patches eq '' and
-	    !defined git_cat_file "$walk:debian") {
+	    !defined git_cat_file "$walk~:debian" and
+	    !quiltify_trees_differ "$walk~", $walk
+	   ) {
 	    # (gdr classification of parent: BreakwaterStart
 	    printdebug "branch_is_gdr  $walk unmarked BreakwaterStart YES\n";
 	    return 1;
@@ -520,11 +548,11 @@ sub protocol_send_file ($$) {
 	my $got = read PF, $d, 65536;
 	die "$ourfn: $!" unless defined $got;
 	last if !$got;
-	print $fh "data-block ".length($d)."\n" or confess $!;
-	print $fh $d or confess $!;
+	print $fh "data-block ".length($d)."\n" or confess "$!";
+	print $fh $d or confess "$!";
     }
     PF->error and die "$ourfn $!";
-    print $fh "data-end\n" or confess $!;
+    print $fh "data-end\n" or confess "$!";
     close PF;
 }
 
@@ -549,9 +577,9 @@ sub protocol_receive_file ($$) {
 	} $fh;
 	last unless $y;
 	my $d = protocol_read_bytes $fh, $l;
-	print PF $d or confess $!;
+	print PF $d or confess "$!";
     }
-    close PF or confess $!;
+    close PF or confess "$!";
 }
 
 #---------- remote protocol support, responder ----------
@@ -561,7 +589,7 @@ sub responder_send_command ($) {
     return unless $we_are_responder;
     # called even without $we_are_responder
     printdebug ">> $command\n";
-    print PO $command, "\n" or confess $!;
+    print PO $command, "\n" or confess "$!";
 }    
 
 sub responder_send_file ($$) {
@@ -596,8 +624,8 @@ sub initiator_expect (&) {
 sub progress {
     if ($we_are_responder) {
 	my $m = join '', @_;
-	responder_send_command "progress ".length($m) or confess $!;
-	print PO $m or confess $!;
+	responder_send_command "progress ".length($m) or confess "$!";
+	print PO $m or confess "$!";
     } else {
 	print @_, "\n";
     }
@@ -612,7 +640,7 @@ sub url_get {
     }
     my $what = $_[$#_];
     progress "downloading $what...";
-    my $r = $ua->get(@_) or confess $!;
+    my $r = $ua->get(@_) or confess "$!";
     return undef if $r->code == 404;
     $r->is_success or fail f_ "failed to fetch %s: %s",
 	$what, $r->status_line;
@@ -676,7 +704,7 @@ Perhaps the upload is stuck in incoming.  Using the version from git.
 END
 
 sub badusage {
-    print STDERR f_ "%s: %s\n%s", $us, "@_", __ $helpmsg or confess $!;
+    print STDERR f_ "%s: %s\n%s", $us, "@_", __ $helpmsg or confess "$!";
     finish 8;
 }
 
@@ -689,7 +717,7 @@ sub pre_help () {
     not_necessarily_a_tree();
 }
 sub cmd_help () {
-    print __ $helpmsg or confess $!;
+    print __ $helpmsg or confess "$!";
     finish 0;
 }
 
@@ -939,8 +967,8 @@ sub supplementary_message ($) {
 	return;
     } elsif ($protovsn >= 3) {
 	responder_send_command "supplementary-message ".length($msg)
-	    or confess $!;
-	print PO $msg or confess $!;
+	    or confess "$!";
+	print PO $msg or confess "$!";
     }
 }
 
@@ -1077,7 +1105,7 @@ sub commit_getclogp ($) {
 }
 
 sub parse_dscdata () {
-    my $dscfh = new IO::File \$dscdata, '<' or confess $!;
+    my $dscfh = new IO::File \$dscdata, '<' or confess "$!";
     printdebug Dumper($dscdata) if $debuglevel>1;
     $dsc = parsecontrolfh($dscfh,$dscurl,1);
     printdebug Dumper($dsc) if $debuglevel>1;
@@ -1295,17 +1323,17 @@ sub aptget_prep ($) {
     cfg_apply_map(\$aptsuites, 'suite map',
 		  access_cfg('aptget-suite-map', 'RETURN-UNDEF'));
 
-    open SRCS, ">", "$aptget_base/$sourceslist" or confess $!;
+    open SRCS, ">", "$aptget_base/$sourceslist" or confess "$!";
     printf SRCS "deb-src %s %s %s\n",
 	access_cfg('mirror'),
 	$aptsuites,
 	access_cfg('aptget-components')
-	or confess $!;
+	or confess "$!";
 
     ensuredir "$aptget_base/cache";
     ensuredir "$aptget_base/lists";
 
-    open CONF, ">", $aptget_configpath or confess $!;
+    open CONF, ">", $aptget_configpath or confess "$!";
     print CONF <<END;
 Debug::NoLocking "true";
 APT::Get::List-Cleanup "false";
@@ -1325,10 +1353,10 @@ END
 			Dir::Etc::preferencesparts
 		      )) {
 	ensuredir "$aptget_base/$key";
-	print CONF "$key \"$quoted_base/$key\";\n" or confess $!;
+	print CONF "$key \"$quoted_base/$key\";\n" or confess "$!";
     };
 
-    my $oldatime = (time // confess $!) - 1;
+    my $oldatime = (time // confess "$!") - 1;
     foreach my $oldlist (<$aptget_base/lists/*Release>) {
 	next unless stat_exists $oldlist;
 	my ($mtime) = (stat _)[9];
@@ -1428,7 +1456,7 @@ sub dummycatapi_run_in_mirror ($@) {
     my @cmd = (qw(sh -ec), 'cd "$1"; shift'."\n".$rune,
 	       qw(x), $mirror, @$argl);
     debugcmd "-|", @cmd;
-    open FIA, "-|", @cmd or confess $!;
+    open FIA, "-|", @cmd or confess "$!";
     my $r = $fn->();
     close FIA or ($!==0 && $?==141) or die failedcmd @cmd;
     return $r;
@@ -1531,7 +1559,7 @@ sub sshpsql ($$$) {
 	       " export LC_MESSAGES=C; export LC_CTYPE=C;".
 	       " ".shellquote qw(psql -A), $dbname, qw(-c), $sql);
     debugcmd "|",@cmd;
-    open P, "-|", @cmd or confess $!;
+    open P, "-|", @cmd or confess "$!";
     while (<P>) {
 	chomp or die;
 	printdebug(">|$_|\n");
@@ -1832,7 +1860,7 @@ sub remove_stray_gits ($) {
     my ($what) = @_;
     my @gitscmd = qw(find -name .git -prune -print0);
     debugcmd "|",@gitscmd;
-    open GITS, "-|", @gitscmd or confess $!;
+    open GITS, "-|", @gitscmd or confess "$!";
     {
 	local $/="\0";
 	while (<GITS>) {
@@ -2197,17 +2225,89 @@ sub check_for_vendor_patches () {
 			  __ "(nominal) distro being accessed");
 }
 
+sub check_bpd_exists () {
+    stat $buildproductsdir
+	or fail f_ "build-products-dir %s is not accessible: %s\n",
+	$buildproductsdir, $!;
+}
+
+sub dotdot_bpd_transfer_origs ($$$) {
+    my ($bpd_abs, $upstreamversion, $wanted) = @_;
+    # checks is_orig_file_of_vsn and if
+    # calls $wanted->{$leaf} and expects boolish
+
+    return if $buildproductsdir eq '..';
+
+    my $warned;
+    my $dotdot = $maindir;
+    $dotdot =~ s{/[^/]+$}{};
+    opendir DD, $dotdot or fail "opendir .. ($dotdot): $!";
+    while ($!=0, defined(my $leaf = readdir DD)) {
+	{
+	    local ($debuglevel) = $debuglevel-1;
+	    printdebug "DD_BPD $leaf ?\n";
+	}
+	next unless is_orig_file_of_vsn $leaf, $upstreamversion;
+	next unless $wanted->($leaf);
+	next if lstat "$bpd_abs/$leaf";
+
+	print STDERR f_
+ "%s: found orig(s) in .. missing from build-products-dir, transferring:\n",
+	    $us
+	    unless $warned++;
+	$! == &ENOENT or fail f_
+	    "check orig file %s in bpd %s: %s", $leaf, $bpd_abs, $!;
+	lstat "$dotdot/$leaf" or fail f_
+	    "check orig file %s in ..: %s", $leaf, $!;
+	if (-l _) {
+	    stat "$dotdot/$leaf" or fail f_
+		"check target of orig symlink %s in ..: %s", $leaf, $!;
+	    my $ltarget = readlink "$dotdot/$leaf" or
+		die "readlink $dotdot/$leaf: $!";
+	    if ($ltarget !~ m{^/}) {
+		$ltarget = "$dotdot/$ltarget";
+	    }
+	    symlink $ltarget, "$bpd_abs/$leaf"
+		or die "$ltarget $bpd_abs $leaf: $!";
+	    print STDERR f_
+ "%s: cloned orig symlink from ..: %s\n",
+		$us, $leaf;
+	} elsif (link "$dotdot/$leaf", "$bpd_abs/$leaf") {
+	    print STDERR f_
+ "%s: hardlinked orig from ..: %s\n",
+		$us, $leaf;
+	} elsif ($! != EXDEV) {
+	    fail f_ "failed to make %s a hardlink to %s: %s",
+		"$bpd_abs/$leaf", "$dotdot/$leaf", $!;
+	} else {
+	    symlink "$bpd_abs/$leaf", "$dotdot/$leaf"
+		or die "$bpd_abs $dotdot $leaf $!";
+	    print STDERR f_
+ "%s: symmlinked orig from .. on other filesystem: %s\n",
+		$us, $leaf;
+	}
+    }
+    die "$dotdot; $!" if $!;
+    closedir DD;
+}
+
 sub generate_commits_from_dsc () {
     # See big comment in fetch_from_archive, below.
     # See also README.dsc-import.
     prep_ud();
     changedir $playground;
 
+    my $bpd_abs = bpd_abs();
+    my $upstreamv = upstreamversion $dsc->{version};
     my @dfi = dsc_files_info();
+
+    dotdot_bpd_transfer_origs $bpd_abs, $upstreamv,
+	sub { grep { $_->{Filename} eq $_[0] } @dfi };
+
     foreach my $fi (@dfi) {
 	my $f = $fi->{Filename};
 	die "$f ?" if $f =~ m#/|^\.|\.dsc$|\.tmp$#;
-	my $upper_f = (bpd_abs()."/$f");
+	my $upper_f = "$bpd_abs/$f";
 
 	printdebug "considering reusing $f: ";
 
@@ -2254,7 +2354,6 @@ sub generate_commits_from_dsc () {
     # from the debian/changelog, so we record the tree objects now and
     # make them into commits later.
     my @tartrees;
-    my $upstreamv = upstreamversion $dsc->{version};
     my $orig_f_base = srcfn $upstreamv, '';
 
     foreach my $fi (@dfi) {
@@ -2289,9 +2388,9 @@ sub generate_commits_from_dsc () {
 		new Dpkg::Compression::Process compression => $cname;
 	    @compr_cmd = $compr_proc->get_uncompress_cmdline();
 	    my $compr_fh = new IO::Handle;
-	    my $compr_pid = open $compr_fh, "-|" // confess $!;
+	    my $compr_pid = open $compr_fh, "-|" // confess "$!";
 	    if (!$compr_pid) {
-		open STDIN, "<&", $input or confess $!;
+		open STDIN, "<&", $input or confess "$!";
 		exec @compr_cmd;
 		die "dgit (child): exec $compr_cmd[0]: $!\n";
 	    }
@@ -2299,23 +2398,23 @@ sub generate_commits_from_dsc () {
 	}
 
 	rmtree "_unpack-tar";
-	mkdir "_unpack-tar" or confess $!;
+	mkdir "_unpack-tar" or confess "$!";
 	my @tarcmd = qw(tar -x -f -
 			--no-same-owner --no-same-permissions
 			--no-acls --no-xattrs --no-selinux);
-	my $tar_pid = fork // confess $!;
+	my $tar_pid = fork // confess "$!";
 	if (!$tar_pid) {
-	    chdir "_unpack-tar" or confess $!;
-	    open STDIN, "<&", $input or confess $!;
+	    chdir "_unpack-tar" or confess "$!";
+	    open STDIN, "<&", $input or confess "$!";
 	    exec @tarcmd;
 	    die f_ "dgit (child): exec %s: %s", $tarcmd[0], $!;
 	}
-	$!=0; (waitpid $tar_pid, 0) == $tar_pid or confess $!;
+	$!=0; (waitpid $tar_pid, 0) == $tar_pid or confess "$!";
 	!$? or failedcmd @tarcmd;
 
 	close $input or
 	    (@compr_cmd ? ($?==SIGPIPE || failedcmd @compr_cmd)
-	     : confess $!);
+	     : confess "$!");
 	# finally, we have the results in "tarball", but maybe
 	# with the wrong permissions
 
@@ -2472,14 +2571,14 @@ END_T
 
     printdebug "import main commit\n";
 
-    open C, ">../commit.tmp" or confess $!;
-    print C <<END or confess $!;
+    open C, ">../commit.tmp" or confess "$!";
+    print C <<END or confess "$!";
 tree $tree
 END
-    print C <<END or confess $! foreach @tartrees;
+    print C <<END or confess "$!" foreach @tartrees;
 parent $_->{Commit}
 END
-    print C <<END or confess $!;
+    print C <<END or confess "$!";
 author $authline
 committer $authline
 
@@ -2488,7 +2587,7 @@ $changes
 [dgit import $treeimporthow $package $cversion]
 END
 
-    close C or confess $!;
+    close C or confess "$!";
     my $rawimport_hash = make_commit qw(../commit.tmp);
 
     if (madformat $dsc->{format}) {
@@ -2533,7 +2632,7 @@ END
 		progress f_ "%s: trying slow absurd-git-apply...", $us;
 		rename "../../gbp-pq-output","../../gbp-pq-output.0"
 		    or $!==ENOENT
-		    or confess $!;
+		    or confess "$!";
 	    }
 	    eval {
 		die "forbid absurd git-apply\n" if $use_absurd
@@ -2599,7 +2698,7 @@ Version actually in archive:   %s (older)
 Last version pushed with dgit: %s (newer or same)
 %s
 END
-		__ $later_warning_msg or confess $!;
+		__ $later_warning_msg or confess "$!";
             @output = $lastpush_mergeinput;
         } else {
 	    # Same version.  Use what's in the server git branch,
@@ -2629,7 +2728,7 @@ sub complete_file_from_dsc ($$;$) {
 	open F, "<", "$tf" or die "$tf: $!";
 	$fi->{Digester}->reset();
 	$fi->{Digester}->addfile(*F);
-	F->error and confess $!;
+	F->error and confess "$!";
 	$got = $fi->{Digester}->hexdigest();
 	return $got eq $fi->{Hash};
     };
@@ -2763,7 +2862,7 @@ sub git_lrfetch_sane {
 	debugcmd "|",@lcmd;
 
 	my %wantr;
-	open GITLS, "-|", @lcmd or confess $!;
+	open GITLS, "-|", @lcmd or confess "$!";
 	while (<GITLS>) {
 	    printdebug "=> ", $_;
 	    m/^(\w+)\s+(\S+)\n/ or die "ls-remote $_ ?";
@@ -3062,6 +3161,7 @@ END
 }
 
 sub fetch_from_archive () {
+    check_bpd_exists();
     ensure_setup_existing_tree();
 
     # Ensures that lrref() is what is actually in the archive, one way
@@ -3184,7 +3284,7 @@ sub fetch_from_archive () {
 	    printdebug "del_lrfetchrefs: $objid $fullrefname\n";
 	    if (!$gur) {
 		$gur ||= new IO::Handle;
-		open $gur, "|-", qw(git update-ref --stdin) or confess $!;
+		open $gur, "|-", qw(git update-ref --stdin) or confess "$!";
 	    }
 	    printf $gur "delete %s %s\n", $fullrefname, $objid;
 	}
@@ -3205,7 +3305,7 @@ Commit referred to by archive: %s
 Last version pushed with dgit: %s
 %s
 END
-		__ $later_warning_msg or confess $!;
+		__ $later_warning_msg or confess "$!";
 	    @mergeinputs = ($lastpush_mergeinput);
 	} else {
 	    # Archive has .dsc which is not a descendant of the last dgit
@@ -3240,11 +3340,11 @@ END
 Package not found in the archive, but has allegedly been pushed using dgit.
 %s
 END
-	    __ $later_warning_msg or confess $!;
+	    __ $later_warning_msg or confess "$!";
     } else {
 	printdebug "nothing found!\n";
 	if (defined $skew_warning_vsn) {
-	    print STDERR f_ <<END, $skew_warning_vsn or confess $!;
+	    print STDERR f_ <<END, $skew_warning_vsn or confess "$!";
 
 Warning: relevant archive skew detected.
 Archive allegedly contains %s
@@ -3310,26 +3410,26 @@ END
 
 	my $mcf = dgit_privdir()."/mergecommit";
 	open MC, ">", $mcf or die "$mcf $!";
-	print MC <<END or confess $!;
+	print MC <<END or confess "$!";
 tree $tree
 END
 
 	my @parents = grep { $_->{Commit} } @mergeinputs;
 	@parents = reverse @parents if $compat_info->{ReverseParents};
-	print MC <<END or confess $! foreach @parents;
+	print MC <<END or confess "$!" foreach @parents;
 parent $_->{Commit}
 END
 
-	print MC <<END or confess $!;
+	print MC <<END or confess "$!";
 author $author
 committer $author
 
 END
 
 	if (defined $compat_info->{Message}) {
-	    print MC $compat_info->{Message} or confess $!;
+	    print MC $compat_info->{Message} or confess "$!";
 	} else {
-	    print MC f_ <<END, $package, $cversion, $csuite or confess $!;
+	    print MC f_ <<END, $package, $cversion, $csuite or confess "$!";
 Record %s (%s) in archive suite %s
 
 Record that
@@ -3338,17 +3438,17 @@ END
 		my ($mi) = (@_);
 		my $mversion = mergeinfo_version $mi;
 		printf MC "  %-20s %s\n", $mversion, $mi->{Info}
-		    or confess $!;
+		    or confess "$!";
 	    };
 
 	    $message_add_info->($mergeinputs[0]);
-	    print MC __ <<END or confess $!;
+	    print MC __ <<END or confess "$!";
 should be treated as descended from
 END
 	    $message_add_info->($_) foreach @mergeinputs[1..$#mergeinputs];
 	}
 
-	close MC or confess $!;
+	close MC or confess "$!";
 	$hash = make_commit $mcf;
     } else {
 	$hash = $mergeinputs[0]{Commit};
@@ -3373,7 +3473,7 @@ END
 	my $got_vsn = getfield $gotclogp, 'Version';
 	printdebug "SKEW CHECK GOT $got_vsn\n";
 	if (version_compare($got_vsn, $skew_warning_vsn) < 0) {
-	    print STDERR f_ <<END, $skew_warning_vsn, $got_vsn or confess $!;
+	    print STDERR f_ <<END, $skew_warning_vsn, $got_vsn or confess "$!";
 
 Warning: archive skew detected.  Using the available version:
 Archive allegedly contains    %s
@@ -3417,12 +3517,12 @@ sub setup_mergechangelogs (;$) {
 	while (<ATTRS>) {
 	    chomp;
 	    next if m{^debian/changelog\s};
-	    print NATTRS $_, "\n" or confess $!;
+	    print NATTRS $_, "\n" or confess "$!";
 	}
-	ATTRS->error and confess $!;
+	ATTRS->error and confess "$!";
 	close ATTRS;
     }
-    print NATTRS "debian/changelog merge=$driver\n" or confess $!;
+    print NATTRS "debian/changelog merge=$driver\n" or confess "$!";
     close NATTRS;
 
     set_local_git_config "$cb.name", __ 'debian/changelog merge driver';
@@ -3478,7 +3578,7 @@ sub is_gitattrs_setup () {
 	printdebug "is_gitattrs_setup: found old macro\n";
 	return 0;
     }
-    $gai->error and confess $!;
+    $gai->error and confess "$!";
     printdebug "is_gitattrs_setup: found nothing\n";
     return undef;
 }    
@@ -3499,8 +3599,8 @@ END
     my $af = "$maindir_gitcommon/info/attributes";
     ensuredir "$maindir_gitcommon/info";
 
-    open GAO, "> $af.new" or confess $!;
-    print GAO <<END, __ <<ENDT or confess $! unless defined $already;
+    open GAO, "> $af.new" or confess "$!";
+    print GAO <<END, __ <<ENDT or confess "$!" unless defined $already;
 *	dgit-defuse-attrs
 $new
 END
@@ -3514,11 +3614,11 @@ ENDT
 		$_ = $new;
 	    }
 	    chomp;
-	    print GAO $_, "\n" or confess $!;
+	    print GAO $_, "\n" or confess "$!";
 	}
-	$gai->error and confess $!;
+	$gai->error and confess "$!";
     }
-    close GAO or confess $!;
+    close GAO or confess "$!";
     rename "$af.new", "$af" or fail f_ "install %s: %s", $af, $!;
 }
 
@@ -3537,7 +3637,7 @@ sub check_gitattrs ($$) {
     my @cmd = (@git, qw(ls-tree -lrz --), "${treeish}:");
     debugcmd "|",@cmd;
     my $gafl = new IO::File;
-    open $gafl, "-|", @cmd or confess $!;
+    open $gafl, "-|", @cmd or confess "$!";
     while (<$gafl>) {
 	chomp or die;
 	s/^\d+\s+\w+\s+\w+\s+(\d+)\t// or die;
@@ -3562,7 +3662,7 @@ sub multisuite_suite_child ($$$) {
     # in child, sets things up, calls $fn->(), and returns undef
     # in parent, returns canonical suite name for $tsuite
     my $canonsuitefh = IO::File::new_tmpfile;
-    my $pid = fork // confess $!;
+    my $pid = fork // confess "$!";
     if (!$pid) {
 	forkcheck_setup();
 	$isuite = $tsuite;
@@ -3570,17 +3670,17 @@ sub multisuite_suite_child ($$$) {
 	$debugprefix .= " ";
 	progress f_ "fetching %s...", $tsuite;
 	canonicalise_suite();
-	print $canonsuitefh $csuite, "\n" or confess $!;
-	close $canonsuitefh or confess $!;
+	print $canonsuitefh $csuite, "\n" or confess "$!";
+	close $canonsuitefh or confess "$!";
 	$fn->();
 	return undef;
     }
-    waitpid $pid,0 == $pid or confess $!;
+    waitpid $pid,0 == $pid or confess "$!";
     fail f_ "failed to obtain %s: %s", $tsuite, waitstatusmsg()
 	if $? && $?!=256*4;
-    seek $canonsuitefh,0,0 or confess $!;
+    seek $canonsuitefh,0,0 or confess "$!";
     local $csuite = <$canonsuitefh>;
-    confess $! unless defined $csuite && chomp $csuite;
+    confess "$!" unless defined $csuite && chomp $csuite;
     if ($? == 256*4) {
 	printdebug "multisuite $tsuite missing\n";
 	return $csuite;
@@ -3723,9 +3823,9 @@ sub fork_for_multisuite ($) {
 }
 
 sub clone_set_head () {
-    open H, "> .git/HEAD" or confess $!;
-    print H "ref: ".lref()."\n" or confess $!;
-    close H or confess $!;
+    open H, "> .git/HEAD" or confess "$!";
+    print H "ref: ".lref()."\n" or confess "$!";
+    close H or confess "$!";
 }
 sub clone_finish ($) {
     my ($dstdir) = @_;
@@ -3758,10 +3858,13 @@ sub clone ($) {
     }
     printdebug "clone main body\n";
 
-    canonicalise_suite();
-    my $hasgit = check_for_git();
     mkdir $dstdir or fail f_ "create \`%s': %s", $dstdir, $!;
     changedir $dstdir;
+    check_bpd_exists();
+
+    canonicalise_suite();
+    my $hasgit = check_for_git();
+
     runcmd @git, qw(init -q);
     record_maindir();
     setup_new_tree();
@@ -3904,18 +4007,18 @@ sub get_source_format () {
 		$options{$_} = 1;
 	    }
 	}
-	F->error and confess $!;
+	F->error and confess "$!";
 	close F;
     } else {
-	confess $! unless $!==&ENOENT;
+	confess "$!" unless $!==&ENOENT;
     }
 
     if (!open F, "debian/source/format") {
-	confess $! unless $!==&ENOENT;
+	confess "$!" unless $!==&ENOENT;
 	return '';
     }
     $_ = <F>;
-    F->error and confess $!;
+    F->error and confess "$!";
     chomp;
     return ($_, \%options);
 }
@@ -4052,7 +4155,7 @@ sub pseudomerge_make_commit ($$$$ $$) {
     # git rev-list --first-parent DTRT.
     my $pmf = dgit_privdir()."/pseudomerge";
     open MC, ">", $pmf or die "$pmf $!";
-    print MC <<END or confess $!;
+    print MC <<END or confess "$!";
 tree $tree
 parent $dgitview
 parent $archive_hash
@@ -4063,7 +4166,7 @@ $msg_msg
 
 [$msg_cmd]
 END
-    close MC or confess $!;
+    close MC or confess "$!";
 
     return make_commit($pmf);
 }
@@ -4243,7 +4346,7 @@ sub push_mktags ($$ $$ $) {
     $dsc->{$ourdscfield[0]} = join " ",
 	$tagwants->[0]{Objid}, $declaredistro, $tagwants->[0]{Tag},
 	$reader_giturl;
-    $dsc->save("$dscfn.tmp") or confess $!;
+    $dsc->save("$dscfn.tmp") or confess "$!";
 
     my $changes = parsecontrol($changesfile,$changesfilewhat);
     foreach my $field (qw(Source Distribution Version)) {
@@ -4266,8 +4369,8 @@ sub push_mktags ($$ $$ $) {
 	my $head = $tw->{Objid};
 	my $tag = $tw->{Tag};
 
-	open TO, '>', $tfn->('.tmp') or confess $!;
-	print TO <<END or confess $!;
+	open TO, '>', $tfn->('.tmp') or confess "$!";
+	print TO <<END or confess "$!";
 object $head
 type commit
 tag $tag
@@ -4278,12 +4381,12 @@ END
 	    print TO f_ <<ENDT, $package, $cversion, $clogsuite, $csuite
 %s release %s for %s (%s) [dgit]
 ENDT
-		or confess $!;
-	    print TO <<END or confess $!;
+		or confess "$!";
+	    print TO <<END or confess "$!";
 [dgit distro=$declaredistro$delibs]
 END
 	    foreach my $ref (sort keys %previously) {
-		print TO <<END or confess $!;
+		print TO <<END or confess "$!";
 [dgit previously:$ref=$previously{$ref}]
 END
 	    }
@@ -4293,12 +4396,12 @@ END
 (maintainer view tag generated by dgit --quilt=%s)
 END
 		$quilt_mode
-		or confess $!;
+		or confess "$!";
 	} else {
 	    confess Dumper($tw)."?";
 	}
 
-	close TO or confess $!;
+	close TO or confess "$!";
 
 	my $tagobjfn = $tfn->('.tmp');
 	if ($sign) {
@@ -4308,7 +4411,7 @@ END
 	    if (!defined $keyid) {
 		$keyid = getfield $clogp, 'Maintainer';
 	    }
-	    unlink $tfn->('.tmp.asc') or $!==&ENOENT or confess $!;
+	    unlink $tfn->('.tmp.asc') or $!==&ENOENT or confess "$!";
 	    my @sign_cmd = (@gpg, qw(--detach-sign --armor));
 	    push @sign_cmd, qw(-u),$keyid if defined $keyid;
 	    push @sign_cmd, $tfn->('.tmp');
@@ -4386,7 +4489,6 @@ END
     push_parse_dsc($dscpath, $dscfn, $cversion);
 
     my $format = getfield $dsc, 'Format';
-    printdebug "format $format\n";
 
     my $symref = git_get_symref();
     my $actualhead = git_rev_parse('HEAD');
@@ -4412,9 +4514,8 @@ END
 
     if (madformat_wantfixup($format)) {
 	# user might have not used dgit build, so maybe do this now:
-	if (quiltmode_splitbrain()) {
+	if ($do_split_brain) {
 	    changedir $playground;
-	    quilt_make_fake_dsc($upstreamversion);
 	    my $cachekey;
 	    ($dgithead, $cachekey) =
 		quilt_check_splitbrain_cache($actualhead, $upstreamversion);
@@ -4422,17 +4523,22 @@ END
  "--quilt=%s but no cached dgit view:
  perhaps HEAD changed since dgit build[-source] ?",
                               $quilt_mode;
-	    $split_brain = 1;
-	    $dgithead = splitbrain_pseudomerge($clogp,
-					       $actualhead, $dgithead,
-					       $archive_hash);
-	    $maintviewhead = $actualhead;
-	    changedir $maindir;
-	    prep_ud(); # so _only_subdir() works, below
-	} else {
+	}
+	if (!$do_split_brain) {
+	    # In split brain mode, do not attempt to incorporate dirty
+	    # stuff from the user's working tree.  That would be mad.
 	    commit_quilty_patch();
 	}
     }
+    if ($do_split_brain) {
+	$made_split_brain = 1;
+	$dgithead = splitbrain_pseudomerge($clogp,
+					   $actualhead, $dgithead,
+					   $archive_hash);
+	$maintviewhead = $actualhead;
+	changedir $maindir;
+	prep_ud(); # so _only_subdir() works, below
+    }
 
     if (defined $overwrite_version && !defined $maintviewhead
 	&& $archive_hash) {
@@ -4459,6 +4565,8 @@ END
 	}
     }
 
+    confess unless !!$made_split_brain == !!$do_split_brain;
+
     changedir $playground;
     progress f_ "checking that %s corresponds to HEAD", $dscfn;
     runcmd qw(dpkg-source -x --),
@@ -4472,7 +4580,7 @@ END
     my $r = system @diffcmd;
     if ($r) {
 	if ($r==256) {
-	    my $referent = $split_brain ? $dgithead : 'HEAD';
+	    my $referent = $made_split_brain ? $dgithead : 'HEAD';
 	    my $diffs = cmdoutput @git, qw(diff --stat), $tree, $dgithead;
 
 	    my @mode_changes;
@@ -4872,6 +4980,7 @@ sub prep_push () {
     parseopts();
     build_or_push_prep_early();
     pushing();
+    build_or_push_prep_modes();
     check_not_dirty();
     my $specsuite;
     if (@ARGV==0) {
@@ -4915,11 +5024,11 @@ sub pre_remote_push_build_host {
     $we_are_responder = 1;
     $us .= " (build host)";
 
-    open PI, "<&STDIN" or confess $!;
-    open STDIN, "/dev/null" or confess $!;
-    open PO, ">&STDOUT" or confess $!;
+    open PI, "<&STDIN" or confess "$!";
+    open STDIN, "/dev/null" or confess "$!";
+    open PO, ">&STDOUT" or confess "$!";
     autoflush PO 1;
-    open STDOUT, ">&STDERR" or confess $!;
+    open STDOUT, ">&STDERR" or confess "$!";
     autoflush STDOUT 1;
 
     $vsnwant //= 1;
@@ -5043,7 +5152,7 @@ sub i_resp_complete {
     $i_child_pid = undef; # prevents killing some other process with same pid
     printdebug "waiting for build host child $pid...\n";
     my $got = waitpid $pid, 0;
-    confess $! unless $got == $pid;
+    confess "$!" unless $got == $pid;
     fail f_ "build host child failed: %s", waitstatusmsg() if $?;
 
     i_cleanup();
@@ -5092,14 +5201,14 @@ sub i_resp_want ($) {
     fail f_ "rpush negotiated protocol version %s".
 	" which does not support quilt mode %s",
 	$protovsn, $quilt_mode
-	if quiltmode_splitbrain;
+	if quiltmode_splitbrain && $protovsn < 4;
 
     my @localpaths = i_method "i_want", $keyword;
     printdebug "[[  $keyword @localpaths\n";
     foreach my $localpath (@localpaths) {
 	protocol_send_file \*RI, $localpath;
     }
-    print RI "files-end\n" or confess $!;
+    print RI "files-end\n" or confess "$!";
 }
 
 our ($i_clogp, $i_version, $i_dscfn, $i_changesfn, @i_buildinfos);
@@ -5206,13 +5315,13 @@ sub quiltify_dpkg_commit ($$$;$) {
     my $descfn = ".git/dgit/quilt-description.tmp";
     open O, '>', $descfn or confess "$descfn: $!";
     $msg =~ s/\n+/\n\n/;
-    print O <<END or confess $!;
+    print O <<END or confess "$!";
 From: $author
 ${xinfo}Subject: $msg
 ---
 
 END
-    close O or confess $!;
+    close O or confess "$!";
 
     {
 	local $ENV{'EDITOR'} = cmdoutput qw(realpath --), $0;
@@ -5295,14 +5404,6 @@ sub quiltify_tree_sentinelfiles ($) {
     return $r;
 }
 
-sub quiltify_splitbrain_needed () {
-    if (!$split_brain) {
-	progress __ "dgit view: changes are required...";
-	runcmd @git, qw(checkout -q -b dgit-view);
-	$split_brain = 1;
-    }
-}
-
 sub quiltify_splitbrain ($$$$$$$) {
     my ($clogp, $unapplied, $headref, $oldtiptree, $diffbits,
 	$editedignores, $cachekey) = @_;
@@ -5322,6 +5423,8 @@ sub quiltify_splitbrain ($$$$$$$) {
     local $ENV{GIT_AUTHOR_EMAIL} = $authline[1];
     local $ENV{GIT_AUTHOR_DATE} =  $authline[2];
 
+    confess unless $do_split_brain;
+
     my $fulldiffhint = sub {
 	my ($x,$y) = @_;
 	my $cmd = "git diff $x $y -- :/ ':!debian'";
@@ -5352,7 +5455,6 @@ END
     }
     if ($quilt_mode =~ m/gbp|unapplied/ &&
 	($diffbits->{O2A} & 01)) { # some patches
-	quiltify_splitbrain_needed();
 	progress __ "dgit view: creating patches-applied version using gbp pq";
 	runcmd shell_cmd 'exec >/dev/null', gbp_pq, qw(import);
 	# gbp pq import creates a fresh branch; push back to dgit-view
@@ -5369,7 +5471,6 @@ END
     }
     if (($diffbits->{O2H} & 02) && # user has modified .gitignore
 	!($diffbits->{O2A} & 02)) { # patches do not change .gitignore
-	quiltify_splitbrain_needed();
 	progress __
 	    "dgit view: creating patch to represent .gitignore changes";
         ensuredir "debian/patches";
@@ -5394,12 +5495,12 @@ ENDU
         close GIPATCH or die "$gipatch: $!";
         runcmd shell_cmd "exec >>$gipatch", @git, qw(diff),
             $unapplied, $headref, "--", sort keys %$editedignores;
-        open SERIES, "+>>", "debian/patches/series" or confess $!;
-        defined seek SERIES, -1, 2 or $!==EINVAL or confess $!;
+        open SERIES, "+>>", "debian/patches/series" or confess "$!";
+        defined seek SERIES, -1, 2 or $!==EINVAL or confess "$!";
         my $newline;
-        defined read SERIES, $newline, 1 or confess $!;
-	print SERIES "\n" or confess $! unless $newline eq "\n";
-	print SERIES "auto-gitignore\n" or confess $!;
+        defined read SERIES, $newline, 1 or confess "$!";
+	print SERIES "\n" or confess "$!" unless $newline eq "\n";
+	print SERIES "auto-gitignore\n" or confess "$!";
 	close SERIES or die  $!;
         runcmd @git, qw(add -f -- debian/patches/series), $gipatch;
         commit_admin +(__ <<END).<<ENDU
@@ -5710,55 +5811,47 @@ sub build_maybe_quilt_fixup () {
 
     check_for_vendor_patches();
 
-    if (quiltmode_splitbrain) {
-	fail <<END unless access_cfg_tagformats_can_splitbrain;
-quilt mode $quilt_mode requires split view so server needs to support
- both "new" and "maint" tag formats, but config says it doesn't.
-END
-    }
-
     my $clogp = parsechangelog();
     my $headref = git_rev_parse('HEAD');
     my $symref = git_get_symref();
-
-    if ($quilt_mode eq 'linear'
-	&& !$fopts->{'single-debian-patch'}
-	&& branch_is_gdr($headref)) {
-	# This is much faster.  It also makes patches that gdr
-	# likes better for future updates without laundering.
-	#
-	# However, it can fail in some casses where we would
-	# succeed: if there are existing patches, which correspond
-	# to a prefix of the branch, but are not in gbp/gdr
-	# format, gdr will fail (exiting status 7), but we might
-	# be able to figure out where to start linearising.  That
-	# will be slower so hopefully there's not much to do.
-	my @cmd = (@git_debrebase,
-		   qw(--noop-ok -funclean-mixed -funclean-ordering
-		      make-patches --quiet-would-amend));
-	# We tolerate soe snags that gdr wouldn't, by default.
-	if (act_local()) {
-	    debugcmd "+",@cmd;
-	    $!=0; $?=-1;
-	    failedcmd @cmd
-		if system @cmd
-		and not ($? == 7*256 or
-			 $? == -1 && $!==ENOENT);
-	} else {
-	    dryrun_report @cmd;
-	}
-	$headref = git_rev_parse('HEAD');
-    }
+    my $upstreamversion = upstreamversion $version;
 
     prep_ud();
     changedir $playground;
 
-    my $upstreamversion = upstreamversion $version;
+    my $splitbrain_cachekey;
+
+    if ($do_split_brain) {
+	my $cachehit;
+	($cachehit, $splitbrain_cachekey) =
+	    quilt_check_splitbrain_cache($headref, $upstreamversion);
+	if ($cachehit) {
+	    changedir $maindir;
+	    return;
+	}
+    }
+
+    unpack_playtree_need_cd_work($headref);
+    if ($do_split_brain) {
+	runcmd @git, qw(checkout -q -b dgit-view);
+	# so long as work is not deleted, its current branch will
+	# remain dgit-view, rather than master, so subsequent calls to
+	#  unpack_playtree_need_cd_work
+	# will DTRT, resetting dgit-view.
+	confess if $made_split_brain;
+	$made_split_brain = 1;
+    }
+    chdir '..';
 
     if ($fopts->{'single-debian-patch'}) {
+	fail f_
+ "quilt mode %s does not make sense (or is not supported) with single-debian-patch",
+	    $quilt_mode
+	    if quiltmode_splitbrain();
 	quilt_fixup_singlepatch($clogp, $headref, $upstreamversion);
     } else {
-	quilt_fixup_multipatch($clogp, $headref, $upstreamversion);
+	quilt_fixup_multipatch($clogp, $headref, $upstreamversion,
+			      $splitbrain_cachekey);
     }
 
     changedir $maindir;
@@ -5766,12 +5859,29 @@ END
         @git, qw(pull --ff-only -q), "$playground/work", qw(master);
 }
 
-sub unpack_playtree_mkwork ($) {
+sub build_check_quilt_splitbrain () {
+    build_maybe_quilt_fixup();
+
+    if ($do_split_brain) {
+	fail <<END unless access_cfg_tagformats_can_splitbrain;
+quilt mode $quilt_mode requires split view so server needs to support
+ both "new" and "maint" tag formats, but config says it doesn't.
+END
+    }
+}
+
+sub unpack_playtree_need_cd_work ($) {
     my ($headref) = @_;
 
-    mkdir "work" or confess $!;
-    changedir "work";
-    mktree_in_ud_here();
+    # prep_ud() must have been called already.
+    if (!chdir "work") {
+	# Check in the filesystem because sometimes we run prep_ud
+	# in between multiple calls to unpack_playtree_need_cd_work.
+	confess "$!" unless $!==ENOENT;
+	mkdir "work" or confess "$!";
+	changedir "work";
+	mktree_in_ud_here();
+    }
     runcmd @git, qw(reset -q --hard), $headref;
 }
 
@@ -5780,17 +5890,20 @@ sub unpack_playtree_linkorigs ($$) {
     # calls $fn->($leafname);
 
     my $bpd_abs = bpd_abs();
+
+    dotdot_bpd_transfer_origs $bpd_abs, $upstreamversion, sub { 1 };
+
     opendir QFD, $bpd_abs or fail "buildproductsdir: $bpd_abs: $!";
-    while ($!=0, defined(my $b = readdir QFD)) {
-	my $f = bpd_abs()."/".$b;
+    while ($!=0, defined(my $leaf = readdir QFD)) {
+	my $f = bpd_abs()."/".$leaf;
 	{
 	    local ($debuglevel) = $debuglevel-1;
-	    printdebug "QF linkorigs $b, $f ?\n";
+	    printdebug "QF linkorigs bpd $leaf, $f ?\n";
 	}
-	next unless is_orig_file_of_vsn $b, $upstreamversion;
-	printdebug "QF linkorigs $b, $f Y\n";
-	link_ltarget $f, $b or die "$b $!";
-        $fn->($b);
+	next unless is_orig_file_of_vsn $leaf, $upstreamversion;
+	printdebug "QF linkorigs $leaf, $f Y\n";
+	link_ltarget $f, $leaf or die "$leaf $!";
+        $fn->($leaf);
     }
     die "$buildproductsdir: $!" if $!;
     closedir QFD;
@@ -5817,7 +5930,7 @@ sub quilt_fixup_singlepatch ($$$) {
     # necessary to build the source package.
 
     unpack_playtree_linkorigs($upstreamversion, sub { });
-    unpack_playtree_mkwork($headref);
+    unpack_playtree_need_cd_work($headref);
 
     rmtree("debian/patches");
 
@@ -5833,13 +5946,18 @@ sub quilt_fixup_singlepatch ($$$) {
     commit_quilty_patch();
 }
 
-sub quilt_make_fake_dsc ($) {
+sub quilt_need_fake_dsc ($) {
+    # cwd should be playground
     my ($upstreamversion) = @_;
 
+    return if stat_exists "fake.dsc";
+    # ^ OK to test this as a sentinel because if we created it
+    # we must either have done the rest too, or crashed.
+
     my $fakeversion="$upstreamversion-~~DGITFAKE";
 
-    my $fakedsc=new IO::File 'fake.dsc', '>' or confess $!;
-    print $fakedsc <<END or confess $!;
+    my $fakedsc=new IO::File 'fake.dsc', '>' or confess "$!";
+    print $fakedsc <<END or confess "$!";
 Format: 3.0 (quilt)
 Source: $package
 Version: $fakeversion
@@ -5847,16 +5965,16 @@ Files:
 END
 
     my $dscaddfile=sub {
-        my ($b) = @_;
+        my ($leaf) = @_;
         
 	my $md = new Digest::MD5;
 
-	my $fh = new IO::File $b, '<' or die "$b $!";
-	stat $fh or confess $!;
+	my $fh = new IO::File $leaf, '<' or die "$leaf $!";
+	stat $fh or confess "$!";
 	my $size = -s _;
 
 	$md->addfile($fh);
-	print $fakedsc " ".$md->hexdigest." $size $b\n" or confess $!;
+	print $fakedsc " ".$md->hexdigest." $size $leaf\n" or confess "$!";
     };
 
     unpack_playtree_linkorigs($upstreamversion, $dscaddfile);
@@ -5873,14 +5991,15 @@ END
     runcmd qw(env GZIP=-1n tar -zcf), "./$debtar", qw(-C), $maindir, @files;
 
     $dscaddfile->($debtar);
-    close $fakedsc or confess $!;
+    close $fakedsc or confess "$!";
 }
 
 sub quilt_fakedsc2unapplied ($$) {
     my ($headref, $upstreamversion) = @_;
     # must be run in the playground
-    # quilt_make_fake_dsc must have been called
+    # quilt_need_fake_dsc must have been called
 
+    quilt_need_fake_dsc($upstreamversion);
     runcmd qw(sh -ec),
         'exec dpkg-source --no-check --skip-patches -x fake.dsc >/dev/null';
 
@@ -5908,6 +6027,8 @@ sub quilt_check_splitbrain_cache ($$) {
     # Computes the cache key and looks in the cache.
     # Returns ($dgit_view_commitid, $cachekey) or (undef, $cachekey)
 
+    quilt_need_fake_dsc($upstreamversion);
+
     my $splitbrain_cachekey;
     
     progress f_
@@ -5939,12 +6060,12 @@ sub quilt_check_splitbrain_cache ($$) {
 	"refs/$splitbraincache", $splitbrain_cachekey;
 
     if ($cachehit) {
-	unpack_playtree_mkwork($headref);
+	unpack_playtree_need_cd_work($headref);
 	my $saved = maybe_split_brain_save $headref, $cachehit, "cache-hit";
 	if ($cachehit ne $headref) {
 	    progress f_ "dgit view: found cached (%s)", $saved;
 	    runcmd @git, qw(checkout -q -b dgit-view), $cachehit;
-	    $split_brain = 1;
+	    $made_split_brain = 1;
 	    return ($cachehit, $splitbrain_cachekey);
 	}
 	progress __ "dgit view: found cached, no changes required";
@@ -5956,7 +6077,7 @@ sub quilt_check_splitbrain_cache ($$) {
 }
 
 sub quilt_fixup_multipatch ($$$) {
-    my ($clogp, $headref, $upstreamversion) = @_;
+    my ($clogp, $headref, $upstreamversion, $splitbrain_cachekey) = @_;
 
     progress f_ "examining quilt state (multiple patches, %s mode)",
 	        $quilt_mode;
@@ -6030,16 +6151,39 @@ sub quilt_fixup_multipatch ($$$) {
     # afterwards with dpkg-source --before-build.  That lets us save a
     # tree object corresponding to .origs.
 
-    my $splitbrain_cachekey;
+    if ($quilt_mode eq 'linear'
+	&& branch_is_gdr($headref)) {
+	# This is much faster.  It also makes patches that gdr
+	# likes better for future updates without laundering.
+	#
+	# However, it can fail in some casses where we would
+	# succeed: if there are existing patches, which correspond
+	# to a prefix of the branch, but are not in gbp/gdr
+	# format, gdr will fail (exiting status 7), but we might
+	# be able to figure out where to start linearising.  That
+	# will be slower so hopefully there's not much to do.
 
-    quilt_make_fake_dsc($upstreamversion);
+	unpack_playtree_need_cd_work $headref;
 
-    if (quiltmode_splitbrain()) {
-	my $cachehit;
-	($cachehit, $splitbrain_cachekey) =
-	    quilt_check_splitbrain_cache($headref, $upstreamversion);
-	return if $cachehit;
+	my @cmd = (@git_debrebase,
+		   qw(--noop-ok -funclean-mixed -funclean-ordering
+		      make-patches --quiet-would-amend));
+	# We tolerate soe snags that gdr wouldn't, by default.
+	if (act_local()) {
+	    debugcmd "+",@cmd;
+	    $!=0; $?=-1;
+	    failedcmd @cmd
+		if system @cmd
+		and not ($? == 7*256 or
+			 $? == -1 && $!==ENOENT);
+	} else {
+	    dryrun_report @cmd;
+	}
+	$headref = git_rev_parse('HEAD');
+
+	chdir '..';
     }
+
     my $unapplied=quilt_fakedsc2unapplied($headref, $upstreamversion);
 
     ensuredir '.pc';
@@ -6058,7 +6202,7 @@ END
 
     changedir '..';
 
-    unpack_playtree_mkwork($headref);
+    unpack_playtree_need_cd_work($headref);
 
     my $mustdeletepc=0;
     if (stat_exists ".pc") {
@@ -6066,7 +6210,7 @@ END
 	progress __ "Tree already contains .pc - will use it then delete it.";
         $mustdeletepc=1;
     } else {
-        rename '../fake/.pc','.pc' or confess $!;
+        rename '../fake/.pc','.pc' or confess "$!";
     }
 
     changedir '../fake';
@@ -6092,9 +6236,9 @@ END
     };
 
     my @dl;
-    foreach my $b (qw(01 02)) {
+    foreach my $bits (qw(01 02)) {
         foreach my $v (qw(O2H O2A H2A)) {
-            push @dl, ($diffbits->{$v} & $b) ? '##' : '==';
+            push @dl, ($diffbits->{$v} & $bits) ? '##' : '==';
         }
     }
     printdebug "differences \@dl @dl.\n";
@@ -6146,7 +6290,7 @@ END
     quiltify($clogp,$headref,$oldtiptree,\@failsuggestion);
 
     if (!open P, '>>', ".pc/applied-patches") {
-	$!==&ENOENT or confess $!;
+	$!==&ENOENT or confess "$!";
     } else {
 	close P;
     }
@@ -6165,21 +6309,21 @@ sub quilt_fixup_editor () {
     open I2, '<', $editing or confess "$editing: $!";
     unlink $editing or confess "$editing: $!";
     open O, '>', $editing or confess "$editing: $!";
-    while (<I1>) { print O or confess $!; } I1->error and confess $!;
+    while (<I1>) { print O or confess "$!"; } I1->error and confess "$!";
     my $copying = 0;
     while (<I2>) {
 	$copying ||= m/^\-\-\- /;
 	next unless $copying;
-	print O or confess $!;
+	print O or confess "$!";
     }
-    I2->error and confess $!;
+    I2->error and confess "$!";
     close O or die $1;
     finish 0;
 }
 
 sub maybe_apply_patches_dirtily () {
     return unless $quilt_mode =~ m/gbp|unapplied/;
-    print STDERR __ <<END or confess $!;
+    print STDERR __ <<END or confess "$!";
 
 dgit: Building, or cleaning with rules target, in patches-unapplied tree.
 dgit: Have to apply the patches - making the tree dirty.
@@ -6203,13 +6347,14 @@ sub maybe_unapply_patches_again () {
 
 #----- other building -----
 
-sub clean_tree_check_git ($$) {
-    my ($honour_ignores, $message) = @_;
+sub clean_tree_check_git ($$$) {
+    my ($honour_ignores, $message, $ignmessage) = @_;
     my @cmd = (@git, qw(clean -dn));
     push @cmd, qw(-x) unless $honour_ignores;
     my $leftovers = cmdoutput @cmd;
     if (length $leftovers) {
-	print STDERR $leftovers, "\n" or confess $!;
+	print STDERR $leftovers, "\n" or confess "$!";
+	$message .= $ignmessage if $honour_ignores;
 	fail $message;
     }
 }
@@ -6219,30 +6364,30 @@ sub clean_tree_check_git_wd ($) {
     return if $cleanmode =~ m{no-check};
     return if $patches_applied_dirtily; # yuk
     clean_tree_check_git +($cleanmode !~ m{all-check}),
-	                  (f_ <<END, $message);
-%s
+	$message, "\n".__ <<END;
 If this is just missing .gitignore entries, use a different clean
-mode, eg --clean=dpkg-source,no-check (-wdu/-wddu) to ignore them
+mode, eg --clean=dpkg-source,no-check (-wdn/-wddn) to ignore them
 or --clean=git (-wg/-wgf) to use \`git clean' instead.
 END
 }
 
 sub clean_tree_check () {
-    # Not yet fully implemented.
     # This function needs to not care about modified but tracked files.
     # That was done by check_not_dirty, and by now we may have run
     # the rules clean target which might modify tracked files (!)
     if ($cleanmode =~ m{^check}) {
 	clean_tree_check_git +($cleanmode =~ m{ignores}), __
- "tree contains uncommitted files and --clean=check specified";
+ "tree contains uncommitted files and --clean=check specified", '';
     } elsif ($cleanmode =~ m{^dpkg-source}) {
 	clean_tree_check_git_wd __
  "tree contains uncommitted files (NB dgit didn't run rules clean)";
     } elsif ($cleanmode =~ m{^git}) {
-	# If we were actually cleaning these files would be summarily
-	# deleted.  Since we're not, and not using the working tree
-	# anyway, we can just ignore them - nothing will use them.
+	clean_tree_check_git 1, __
+ "tree contains uncommited, untracked, unignored files\n".
+ "You can use --clean=git[-ff],always (-wga/-wgfa) to delete them.", '';
     } elsif ($cleanmode eq 'none') {
+    } else {
+	confess "$cleanmode ?";
     }
 }
 
@@ -6257,15 +6402,15 @@ sub clean_tree () {
 	runcmd_ordryrun_local @cmd;
 	clean_tree_check_git_wd __
  "tree contains uncommitted files (after running rules clean)";
-    } elsif ($cleanmode eq 'git') {
+    } elsif ($cleanmode =~ m{^git(?!-)}) {
 	runcmd_ordryrun_local @git, qw(clean -xdf);
-    } elsif ($cleanmode eq 'git-ff') {
+    } elsif ($cleanmode =~ m{^git-ff}) {
 	runcmd_ordryrun_local @git, qw(clean -xdff);
     } elsif ($cleanmode =~ m{^check}) {
 	clean_tree_check();
     } elsif ($cleanmode eq 'none') {
     } else {
-	die "$cleanmode ?";
+	confess "$cleanmode ?";
     }
 }
 
@@ -6292,19 +6437,33 @@ sub build_or_push_prep_early () {
     $dscfn = dscfn($version);
 }
 
+sub build_or_push_prep_modes () {
+    my ($format,) = get_source_format();
+    printdebug "format $format, quilt mode $quilt_mode\n";
+    if (madformat_wantfixup($format) && quiltmode_splitbrain()) {
+	$do_split_brain = 1;
+    }
+    fail __ "dgit: --include-dirty is not supported in split view quilt mode"
+	if $do_split_brain && $includedirty;
+}
+
 sub build_prep_early () {
     build_or_push_prep_early();
     notpushing();
+    build_or_push_prep_modes();
     check_not_dirty();
 }
 
 sub build_prep ($) {
     my ($wantsrc) = @_;
     build_prep_early();
-    if (!building_source_in_playtree() || ($wantsrc & WANTSRC_BUILDER)) {
+    check_bpd_exists();
+    if (!building_source_in_playtree() || ($wantsrc & WANTSRC_BUILDER)
 	# Clean the tree because we're going to use the contents of
 	# $maindir.  (We trying to include dirty changes in the source
 	# package, or we are running the builder in $maindir.)
+	|| $cleanmode =~ m{always}) {
+	# Or because the user asked us to.
 	clean_tree();
     } else {
 	# We don't actually need to do anything in $maindir, but we
@@ -6313,7 +6472,7 @@ sub build_prep ($) {
 	# said -wc we should still do the check.
 	clean_tree_check();
     }
-    build_maybe_quilt_fixup();
+    build_check_quilt_splitbrain();
     if ($rmchanges) {
 	my $pat = changespat $version;
 	foreach my $f (glob "$buildproductsdir/$pat") {
@@ -6464,7 +6623,7 @@ END
 	        "@changesfiles";
     }
     printdone f_ "build successful, results in %s\n", $result
-	or confess $!;
+	or confess "$!";
 }
 
 sub midbuild_checkchanges () {
@@ -6562,7 +6721,7 @@ sub cmd_gbp_build {
     if ($gbp_make_orig) {
 	my $priv = dgit_privdir();
 	my $ok = "$priv/origs-gen-ok";
-	unlink $ok or $!==&ENOENT or confess $!;
+	unlink $ok or $!==&ENOENT or confess "$!";
 	my @origs_cmd = @cmd;
 	push @origs_cmd, qw(--git-cleaner=true);
 	push @origs_cmd, "--git-prebuild=".
@@ -6602,7 +6761,7 @@ sub building_source_in_playtree {
     #
     # Note that if we are building a source package in split brain
     # mode we do not support including uncommitted changes, because
-    # that makes quilt fixup too hard.  I.e. ($split_brain && (dgit is
+    # that makes quilt fixup too hard.  I.e. ($made_split_brain && (dgit is
     # building a source package)) => !$includedirty
     return !$includedirty;
 }
@@ -6613,6 +6772,8 @@ sub build_source {
 	unlink "$buildproductsdir/$sourcechanges" or $!==ENOENT
 	    or fail f_ "remove %s: %s", $sourcechanges, $!;
     }
+    confess unless !!$made_split_brain == !!$do_split_brain;
+
     my @cmd = (@dpkgsource, qw(-b --));
     my $leafdir;
     if (building_source_in_playtree()) {
@@ -6621,12 +6782,12 @@ sub build_source {
         # If we are in split brain, there is already a playtree with
         # the thing we should package into a .dsc (thanks to quilt
         # fixup).  If not, make a playtree
-        prep_ud() unless $split_brain;
+        prep_ud() unless $made_split_brain;
         changedir $playground;
-        unless ($split_brain) {
+        unless ($made_split_brain) {
             my $upstreamversion = upstreamversion $version;
             unpack_playtree_linkorigs($upstreamversion, sub { });
-            unpack_playtree_mkwork($headref);
+            unpack_playtree_need_cd_work($headref);
             changedir '..';
         }
     } else {
@@ -6693,7 +6854,7 @@ sub cmd_push_source {
 	"dgit push-source: --include-dirty/--ignore-dirty does not make".
 	"sense with push-source!"
 	if $includedirty;
-    build_maybe_quilt_fixup();
+    build_check_quilt_splitbrain();
     if ($changesfile) {
         my $changes = parsecontrol("$buildproductsdir/$changesfile",
                                    __ "source changes file");
@@ -6792,9 +6953,8 @@ sub cmd_print_unapplied_treeish {
     prep_ud();
     changedir $playground;
     my $uv = upstreamversion $version;
-    quilt_make_fake_dsc($uv);
     my $u = quilt_fakedsc2unapplied($headref, $uv);
-    print $u, "\n" or confess $!;
+    print $u, "\n" or confess "$!";
 }
 
 sub import_dsc_result {
@@ -6921,29 +7081,49 @@ END
     my @dfi = dsc_files_info();
     foreach my $fi (@dfi) {
 	my $f = $fi->{Filename};
+	# We transfer all the pieces of the dsc to the bpd, not just
+	# origs.  This is by analogy with dgit fetch, which wants to
+	# keep them somewhere to avoid downloading them again.
+	# We make symlinks, though.  If the user wants copies, then
+	# they can copy the parts of the dsc to the bpd using dcmd,
+	# or something.
 	my $here = "$buildproductsdir/$f";
 	if (lstat $here) {
-	    next if stat $here;
+	    if (stat $here) {
+		next;
+	    }
 	    fail f_ "lstat %s works but stat gives %s !", $here, $!;
 	}
 	fail f_ "stat %s: %s", $here, $! unless $! == ENOENT;
+	printdebug "not in bpd, $f ...\n";
+	# $f does not exist in bpd, we need to transfer it
 	my $there = $dscfn;
-	if ($dscfn =~ m#^(?:\./+)?\.\./+#) {
-	    $there = $';
-	} elsif ($dscfn =~ m#^/#) {
-	    $there = $dscfn;
+	$there =~ s{[^/]+$}{$f} or confess "$there ?";
+	# $there is file we want, relative to user's cwd, or abs
+	printdebug "not in bpd, $f, test $there ...\n";
+	stat $there or fail f_
+	    "import %s requires %s, but: %s", $dscfn, $there, $!;
+	if ($there =~ m#^(?:\./+)?\.\./+#) {
+	    # $there is relative to user's cwd
+	    my $there_from_parent = $';
+	    if ($buildproductsdir !~ m{^/}) {
+		# abs2rel, despite its name, can take two relative paths
+		$there = File::Spec->abs2rel($there,$buildproductsdir);
+		# now $there is relative to bpd, great
+		printdebug "not in bpd, $f, abs2rel, $there ...\n";
+	    } else {
+		$there = (dirname $maindir)."/$there_from_parent";
+		# now $there is absoute
+		printdebug "not in bpd, $f, rel2rel, $there ...\n";
+	    }
+	} elsif ($there =~ m#^/#) {
+	    # $there is absolute already
+	    printdebug "not in bpd, $f, abs, $there ...\n";
 	} else {
 	    fail f_
 		"cannot import %s which seems to be inside working tree!",
 		$dscfn;
 	}
-	$there =~ s#/+[^/]+$## or fail f_
-	    "import %s requires .../%s, but it does not exist",
-	    $dscfn, $f;
-	$there .= "/$f";
-	my $test = $there =~ m{^/} ? $there : "../$there";
-	stat $test or fail f_
-	    "import %s requires %s, but: %s", $dscfn, $test, $!;
 	symlink $there, $here or fail f_
 	    "symlink %s to %s: %s", $there, $here, $!;
 	progress f_ "made symlink %s -> %s", $here, $there;
@@ -7025,7 +7205,7 @@ sub cmd_print_dgit_repos_server_source_url {
 	"no arguments allowed to dgit print-dgit-repos-server-source-url"
 	if @ARGV;
     my $url = repos_server_url();
-    print $url, "\n" or confess $!;
+    print $url, "\n" or confess "$!";
 }
 
 sub pre_print_dpkg_source_ignores {
@@ -7035,7 +7215,7 @@ sub cmd_print_dpkg_source_ignores {
     badusage __
 	"no arguments allowed to dgit print-dpkg-source-ignores"
 	if @ARGV;
-    print "@dpkg_source_ignores\n" or confess $!;
+    print "@dpkg_source_ignores\n" or confess "$!";
 }
 
 sub cmd_setup_mergechangelogs {
@@ -7066,7 +7246,7 @@ sub cmd_setup_new_tree {
 #---------- argument parsing and main program ----------
 
 sub cmd_version {
-    print "dgit version $our_version\n" or confess $!;
+    print "dgit version $our_version\n" or confess "$!";
     finish 0;
 }
 
@@ -7190,6 +7370,12 @@ sub parseopts () {
 		     ($om = $opts_opt_map{$1})) {
 		push @ropts, $_;
 		push @$om, $2;
+	    } elsif (m/^--([-0-9a-z]+)\!:(.*)/s &&
+		     !$opts_opt_cmdonly{$1} &&
+		     ($om = $opts_opt_map{$1})) {
+		push @ropts, $_;
+		my $cmd = shift @$om;
+		@$om = ($cmd, grep { $_ ne $2 } @$om);
 	    } elsif (m/^--(gbp|dpm)$/s) {
 		push @ropts, "--quilt=$1";
 		$quilt_mode = $1;
@@ -7279,12 +7465,11 @@ sub parseopts () {
 		} elsif (s/^-wn$//s) {
 		    push @ropts, $&;
 		    $cleanmode = 'none';
-		} elsif (s/^-wg$//s) {
+		} elsif (s/^-wg(f?)(a?)$//s) {
 		    push @ropts, $&;
 		    $cleanmode = 'git';
-		} elsif (s/^-wgf$//s) {
-		    push @ropts, $&;
-		    $cleanmode = 'git-ff';
+		    $cleanmode .= '-ff' if $1;
+		    $cleanmode .= ',always' if $2;
 		} elsif (s/^-wd(d?)([na]?)$//s) {
 		    push @ropts, $&;
 		    $cleanmode = 'dpkg-source';
@@ -7318,7 +7503,7 @@ sub parseopts () {
 
 sub check_env_sanity () {
     my $blocked = new POSIX::SigSet;
-    sigprocmask SIG_UNBLOCK, $blocked, $blocked or confess $!;
+    sigprocmask SIG_UNBLOCK, $blocked, $blocked or confess "$!";
 
     eval {
 	foreach my $name (qw(PIPE CHLD)) {
@@ -7399,9 +7584,6 @@ sub parseopts_late_defaults () {
 	$$vr = $v;
     }
 
-    fail __ "dgit: --include-dirty is not supported in split view quilt mode"
-	if $split_brain && $includedirty;
-
     if (!defined $cleanmode) {
 	local $access_forpush;
 	$cleanmode = access_cfg('clean-mode-newer', 'RETURN-UNDEF');
@@ -7435,7 +7617,7 @@ print STDERR __ "DRY RUN ONLY\n" if $dryrun_level > 1;
 print STDERR __ "DAMP RUN - WILL MAKE LOCAL (UNSIGNED) CHANGES\n"
     if $dryrun_level == 1;
 if (!@ARGV) {
-    print STDERR __ $helpmsg or confess $!;
+    print STDERR __ $helpmsg or confess "$!";
     finish 8;
 }
 $cmd = $subcommand = shift @ARGV;