avoid rewrite

diff --git a/git-debrebase b/git-debrebase
index 2f37196abda0e4d52bab634b68e1e6675d0df327..44ee02f46bae76acc7383c9dd189b7f7745faef8 100755 (executable)
--- a/git-debrebase
+++ b/git-debrebase
@@ -328,11 +328,13 @@ sub launder ($$$) {
  
     my $committer_authline = calculate_committer_authline();
 
+    my $need_rewrite = 0;
+
     in_workarea sub {
        mkdir $rd or $!==EEXIST or die $!;
-
        my $current_method;
-       foreach my $cl (qw(Debian), @deb_cl, qw(Upstream), @ups_cl) {
+       foreach my $cl (qw(Debian), (reverse @deb_cl),
+                       qw(Upstream), (reverse @ups_cl)) {
            if (!ref $cl) {
                $current_method = $cl;
                next;
@@ -347,21 +349,39 @@ sub launder ($$$) {
            } elsif ($method eq 'DgitImportDebianUpdate') {
                $read_tree_debian->($cltree);
                $rm_tree_cached(qw(debian/patches));
+               $need_rewrite = 1;
            } elsif ($method eq 'DgitImportUpstreamUpdate') {
                $read_tree_upstream->($cltree);
                push @parents, map { $_->{CommitId} } @{ $cl->{OrigParents} };
+               $need_rewrite = 1;
            } else {
                confess "$method ?";
            }
            my $newtree = cmdoutput @git, qw(write-tree);
-           my $ch = $cl->{Msg};
+           my $ch = $cl->{Hdr};
            $ch =~ s{^tree .*}{tree $newtree}m or confess "$ch ?";
-           $ch =~ s{^committer .*$}{$committer_authline}m or confess "$ch ?";
-           open CD, ">", "$rd/m" or die $!;
-           print CD $ch, "\n", $cl->{Msg}; or die $!;
-           close CD or die $!;
-           my $newcommit = cmdoutput @git, qw(hash-object -t commit), "$rd/m";
-           $build = $newcommit;
+           $ch =~ s{^parent .*\n}{}m;
+           $ch =~ s{(?=^author}{
+               map { "parent $_\n" } @parents
+           }me or confess "$ch ?";
+           foreach my $rewrite ($need_rewrite ? 1 : qw(0 1)) {
+               if ($rewrite) {
+                   $ch =~ s{^committer .*$}{$committer_authline}m
+                       or confess "$ch ?";
+                   $need_rewrite = 1;
+               }
+               my $cf = "$rd/m$rewrite"
+               open CD, ">", $cf or die $!;
+               print CD $ch, "\n", $cl->{Msg}; or die $!;
+               close CD or die $!;
+               my @cmd = (@git, qw(hash-object));
+               push @cmd, qw(-w) if $rewrite;
+               push @cmd, qw(-t commit), $cf;
+               my $newcommit = cmdoutput @cmd;
+               next unless $rewrite or $newcommit eq $cl->{CommitId};
+               $build = $newcommit;
+               last;
+           }
        }
     };