dgit: HEAD/.dsc mismatch error: Much better message

Closes:#809516.

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

1 files changed, 9 insertions, 6 deletions

diff --git a/dgit b/dgit
index 7b16ff3..469f6bf 100755
--- a/dgit
+++ b/dgit
@@ -3211,17 +3211,20 @@ END
     my ($tree,$dir) = mktree_in_ud_from_only_subdir();
     check_for_vendor_patches() if madformat($dsc->{format});
     changedir '../../../..';
-    my $diffopt = $debuglevel>0 ? '--exit-code' : '--quiet';
-    my @diffcmd = (@git, qw(diff), $diffopt, $tree, $dgithead);
+    my @diffcmd = (@git, qw(diff --quiet), $tree, $dgithead);
     debugcmd "+",@diffcmd;
     $!=0; $?=-1;
     my $r = system @diffcmd;
     if ($r) {
 	if ($r==256) {
-	    fail "$dscfn specifies a different tree to your HEAD commit;".
-		" perhaps you forgot to build".
-		($diffopt eq '--exit-code' ? "" :
-		 " (run with -D to see full diff output)");
+	    my $diffs = cmdoutput @git, qw(diff --stat), $tree, $dgithead;
+	    fail <<END
+HEAD specifies a different tree to $dscfn:
+$diffs
+Perhaps you forgot to build.  Or perhaps there is a problem with your
+ source tree (see dgit(7) for some hints).  To see a full diff, run
+   git diff $tree HEAD
+END
 	} else {
 	    failedcmd @diffcmd;
 	}