p5326: create missing 'perf-tag' tag

Some of the tests in test_full_bitmap rely on having a tag named
perf-tag in place. We could create it in test_full_bitmap(), but we want
to have it in place before the repack starts.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/perf/p5326-multi-pack-bitmaps.sh

@@ -10,6 +10,12 @@ test_expect_success 'enable multi-pack index' '
 	git config core.multiPackIndex true
 '
 
+# we need to create the tag up front such that it is covered by the repack and
+# thus by generated bitmaps.
+test_expect_success 'create tags' '
+	git tag --message="tag pointing to HEAD" perf-tag HEAD
+'
+
 test_perf 'setup multi-pack index' '
 	git repack -ad &&
 	git multi-pack-index write --bitmap