t7700: demonstrate misbehavior of 'repack -a' when local packs exist

The ability to "...fatten [the] local repository by packing everything that
is needed by the local ref into a single new pack, including things that are
borrowed from alternates"[1] is supposed to be provided by the '-a' or '-A'
options to repack when '-l' is not used, but there is a flaw.  For each
pack in the local repository without a .keep file, repack supplies a
--unpacked=<pack> argument to pack-objects.

The --unpacked option to pack-objects, with or without an argument, causes
pack-objects to ignore any object which is packed in a pack not mentioned
in an argument to --unpacked=.  So, if there are local packs, and
'repack -a' is called, then any objects which reside in packs accessible
through alternates will _not_ be packed.  If there are no local packs, then
no --unpacked argument will be supplied, and repack will behave as expected.

[1] http://mid.gmane.org/7v8wrwidi3.fsf@gitster.siamese.dyndns.orgSigned-off-by: NBrandon Casey <casey@nrlssc.navy.mil>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

t/t7700-repack.sh

@@ -69,5 +69,24 @@ test_expect_success 'packed obs in alt ODB are repacked even when local repo is
 	done
 '
 
+test_expect_failure 'packed obs in alt ODB are repacked when local repo has packs' '
+	rm -f .git/objects/pack/* &&
+	echo new_content >> file1 &&
+	git add file1 &&
+	git commit -m more_content &&
+	git repack &&
+	git repack -a -d &&
+	myidx=$(ls -1 .git/objects/pack/*.idx) &&
+	test -f "$myidx" &&
+	for p in alt_objects/pack/*.idx; do
+		git verify-pack -v $p | sed -n -e "/^[0-9a-f]\{40\}/p"
+	done | while read sha1 rest; do
+		if ! ( git verify-pack -v $myidx | grep "^$sha1" ); then
+			echo "Missing object in local pack: $sha1"
+			return 1
+		fi
+	done
+'
+
 test_done