[PATCH] pack-objects: don't warn about bitmaps on incremental pack

[David Turner <dturner@twosigma.com>]

When running git pack-objects --incremental, we do not expect to be
able to write a bitmap; it is very likely that objects in the new pack
will have references to objects outside of the pack.  So we don't need
to warn the user about it.

This warning was making its way into gc.log because auto-gc will do an
incremental repack when there are too many loose objects but not too
many packs.  When the gc.log was present, future auto gc runs would
refuse to run.

Signed-off-by: David Turner <dturner@twosigma.com>
---
 builtin/pack-objects.c  |  3 ++-
 t/t5310-pack-bitmaps.sh | 12 ++++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index 0fd52bd..96de213 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -1083,7 +1083,8 @@ static int add_object_entry(const unsigned char *sha1, enum object_type type,
 	if (!want_object_in_pack(sha1, exclude, &found_pack, &found_offset)) {
 		/* The pack is missing an object, so it will not have closure */
 		if (write_bitmap_index) {
-			warning(_(no_closure_warning));
+			if (!incremental)
+				warning(_(no_closure_warning));
 			write_bitmap_index = 0;
 		}
 		return 0;
diff --git a/t/t5310-pack-bitmaps.sh b/t/t5310-pack-bitmaps.sh
index b4c7a6f..d81636e 100755
--- a/t/t5310-pack-bitmaps.sh
+++ b/t/t5310-pack-bitmaps.sh
@@ -247,6 +247,18 @@ test_expect_success 'pack-objects respects --incremental' '
 	test_cmp 4.objects objects
 '
 
+test_expect_success 'incremental repack does not create bitmaps' '
+	test_commit 11 &&
+	ls .git/objects/pack/ | grep bitmap >existing_bitmaps &&
+	ls .git/objects/pack/ | grep -v bitmap >existing_packs &&
+	git repack -d 2>err &&
+	test_line_count = 0 err &&
+	ls .git/objects/pack/ | grep bitmap >output &&
+	ls .git/objects/pack/ | grep -v bitmap >post_packs &&
+	test_cmp existing_bitmaps output &&
+	! test_cmp existing_packs post_packs
+'
+
 test_expect_success 'pack with missing blob' '
 	rm $(objpath $blob) &&
 	git pack-objects --stdout --revs <revs >/dev/null
-- 
2.8.0.rc4.22.g8ae061a