X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=git-debrebase;h=4bfe0952518214203c5e3ac397b27c53ceb93354;hb=52b97bd1b16a5db0b3b58e4864b5fdd6fc5e2689;hp=484fcdca01644b0fec740d51e1ddfade437591eb;hpb=849364df60ca1dfedfbd23597fdab6a98881cb19;p=dgit.git

diff --git a/git-debrebase b/git-debrebase
index 484fcdca..4bfe0952 100755
--- a/git-debrebase
+++ b/git-debrebase
@@ -441,7 +441,44 @@ sub record_gdrlast ($$;$) {
 
 sub fail_unprocessable ($) {
     my ($msg) = @_;
-    fail $msg;
+    changedir $maindir;
+    my ($ffqs, $ffqm, $symref, $ffq_prev, $gdrlast) = ffq_prev_branchinfo();
+
+    my $mangled = <<END;
+Branch/history seems mangled - no longer in gdr format.
+See ILLEGAL OPERATIONS in git-debrebase(5).
+END
+    chomp $mangled;
+
+    if (defined $ffqm) {
+	fail <<END;
+$msg
+Is this meant to be a gdr branch?  $ffqm
+END
+    } elsif (git_get_ref $ffq_prev) {
+	fail <<END;
+$msg
+$mangled
+Consider git-debrebase scrap, to throw away your recent work.
+END
+    } elsif (!git_get_ref $gdrlast) {
+	fail <<END;
+$msg
+Branch does not seem to be meant to be a git-debrebase branch?
+Wrong branch, or maybe you needed git-debrebase convert-from-*.
+END
+    } elsif (is_fast_fwd $gdrlast, git_rev_parse 'HEAD') {
+	fail <<END;
+$msg
+$mangled
+END
+    } else {
+	fail <<END;
+$msg
+Branch/history mangled, and diverged since last git-debrebase.
+Maybe you reset to, or rebased from, somewhere inappropriate.
+END
+    }
 };
 
 sub gbp_pq_export ($$$) {