builtin/rev-list: fix leaking bitmap index when calculating disk usage

git-rev-list(1) can speed up its object size calculations for reachable
objects via a bitmap walk, if there is any bitmap. This is done in
`try_bitmap_disk_usage()`, which tries to optimistically load the bitmap
and then use it, if available. It never frees it though, leading to a
memory leak. Fix this.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/rev-list.c

@@ -508,6 +508,8 @@ static int try_bitmap_disk_usage(struct rev_info *revs,
 
 	size_from_bitmap = get_disk_usage_from_bitmap(bitmap_git, revs);
 	print_disk_usage(size_from_bitmap);
+
+	free_bitmap_index(bitmap_git);
 	return 0;
 }
 

t/t6115-rev-list-du.sh

@@ -1,6 +1,8 @@
 #!/bin/sh
 
 test_description='basic tests of rev-list --disk-usage'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 # we want a mix of reachable and unreachable, as well as