dgit: unrepres. changes: Tolerate creation of symlinks

Experimentally, dpkg-source on stretch will create patches to create
new symlinks.  (It will fail on attempts to modify existing symlinks
and it ignores attempts to change plain file executability.)

Implementation: add an alternative which tolerates the git symlink
mode.  This replaces the check on $oldmode, which in this context we
know is all 0s and can therefore never match.

While we're here, change the error message.

Closes:#857382.

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

3 files changed, 5 insertions, 4 deletions

diff --git a/debian/changelog b/debian/changelog
index 478ad5f..aaaee20 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -9,6 +9,7 @@ dgit (3.12~) unstable; urgency=medium
   * dgit import: Right error message for missing files in ..
   * dgit import: Avoid making broken symlinks in ..
   * quilt fixup: Tolerate deletion of executable files.
+  * quilt fixup: Tolerate symlink creation (make patches).  Closes:#857382.
 
   Important bugfixes to other components:
   * dgit-repos-server: Do not reject commits with no author/committer
diff --git a/dgit b/dgit
index d1bf213..42647ce 100755
--- a/dgit
+++ b/dgit
@@ -4924,9 +4924,9 @@ sub quiltify_trees_differ ($$;$$$) {
 			unless $oldmode =~ m/^10/;
 		} else {
 		    # creation
-		    die "non-default mode or type\n"
-			unless $newmode =~ m/^100644$/ ||
-			       $oldmode =~ m/^100644$/;
+		    die "creation with non-default mode\n"
+			unless $newmode =~ m/^100644$/ or
+			       $newmode =~ m/^120000$/;
 		}
 	    };
 	    if ($@) {
diff --git a/tests/tests/unrepresentable b/tests/tests/unrepresentable
index 80b5a05..89df719 100755
--- a/tests/tests/unrepresentable
+++ b/tests/tests/unrepresentable
@@ -44,7 +44,7 @@ badly-1 src.c 'mode or type changed'
 	git add src.c
 badly-2
 
-badly-1 new 'non-default mode'
+badly-1 new 'creation with non-default mode'
 	echo hi >new
 	chmod 755 new
 	git add new