repack: silence warnings when auto-enabled bitmaps cannot be built

Depending on various config options, a full repack may not be able to
build a reachability bitmap index (e.g., if pack.packSizeLimit forces us
to write multiple packs). In these cases pack-objects may write a
warning to stderr.

Since 36eba0323d (repack: enable bitmaps by default on bare repos,
2019-03-14), we may generate these warnings even when the user did not
explicitly ask for bitmaps. This has two downsides:

  - it can be confusing, if they don't know what bitmaps are

  - a daemonized auto-gc will write this to its log file, and the
    presence of the warning may suppress further auto-gc (until
    gc.logExpiry has elapsed)

Let's have repack communicate to pack-objects that the choice to turn on
bitmaps was not made explicitly by the user, which in turn allows
pack-objects to suppress these warnings.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/t/t7700-repack.sh b/t/t7700-repack.sh
index 8d9a358df8..54f815b8b9 100755
--- a/t/t7700-repack.sh
+++ b/t/t7700-repack.sh
@@ -250,4 +250,15 @@ test_expect_success 'no bitmaps created if .keep files present' '
 	test_must_be_empty actual
 '
 
+test_expect_success 'auto-bitmaps do not complain if unavailable' '
+	test_config -C bare.git pack.packSizeLimit 1M &&
+	blob=$(test-tool genrandom big $((1024*1024)) |
+	       git -C bare.git hash-object -w --stdin) &&
+	git -C bare.git update-ref refs/tags/big $blob &&
+	git -C bare.git repack -ad 2>stderr &&
+	test_must_be_empty stderr &&
+	find bare.git/objects/pack -type f -name "*.bitmap" >actual &&
+	test_must_be_empty actual
+'
+
 test_done