From 71350fe30f7449b24dc2884b42cc5ff50a2bf84e Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Sat, 4 Jun 2016 15:04:28 +0100
Subject: [PATCH] Split brain: Make quiltify_trees_differ cleverer

Have it be able to explain what was different, by returning a bitmask.
Update the call sites.

Incidentally, fix a bug where .gitignores other than in the toplevel
would not be ignored when they ought to have been.
---
 debian/changelog |  2 ++
 dgit             | 23 ++++++++++++++---------
 2 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/debian/changelog b/debian/changelog
index 5842873f..30db5c98 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -22,6 +22,8 @@ dgit (1.5~~) unstable; urgency=medium
     Instead, insist on a single one.
   * dgit sbuild no longer deletes extranious .changes files; instead
     we rely on --rm-old-changes, or failing that, fail early.
+  * When doing quilt linearisation, treat upstream .gitignores not
+    in the toplevel the same way we treat ones in the toplevel.
 
   Infrastructure:
   * Better error handling in dgit-repos-policy-debian.
diff --git a/dgit b/dgit
index c64f0fe4..0c8183dc 100755
--- a/dgit
+++ b/dgit
@@ -2511,17 +2511,22 @@ END
 }
 
 sub quiltify_trees_differ ($$;$) {
-    my ($x,$y,$ignoregitignore) = @_;
-    # returns 1 iff the two tree objects differ other than in debian/
+    my ($x,$y,$finegrained) = @_;
+    # returns true iff the two tree objects differ other than in debian/
+    # returns bitmas 01 - differ in upstream files except .gitignore
+    #                02 - differ in .gitignore
     local $/=undef;
-    my @cmd = (@git, qw(diff-tree --name-only -z), $x, $y);
+    my @cmd = (@git, qw(diff-tree --name-only -z));
+    push @cmd, qw(-r) if $finegrained;
+    push @cmd, $x, $y;
     my $diffs= cmdoutput @cmd;
+    my $r = 0;
     foreach my $f (split /\0/, $diffs) {
-	next if $f eq 'debian';
-	next if $f eq '.gitignore' && $ignoregitignore;
-	return 1;
+	next if $f =~ m#^debian(?:/.*)?$#s;
+	$r |= ($f =~ m#^(?:.*/)?.gitignore$#s) ? 02 : 01;
     }
-    return 0;
+    printdebug "quiltify_trees_differ $x $y => $r\n";
+    return $r;
 }
 
 sub quiltify_tree_sentinelfiles ($) {
@@ -2536,8 +2541,8 @@ sub quiltify_tree_sentinelfiles ($) {
 sub quilt_could_gbp ($$$) {
     my ($userhead,$unapplied,$applied) = @_;
     return
-	!quiltify_trees_differ($userhead,$unapplied,1) &&
-	quiltify_trees_differ($userhead,$applied,1);
+	!(quiltify_trees_differ($userhead,$unapplied,1) & 01) &&
+	(quiltify_trees_differ($userhead,$applied,1) & 01);
 }
 
 sub quiltify ($$$$) {
-- 
2.30.2