pack-objects: call release_revisions() after cruft traversal

enumerate_and_traverse_cruft_objects() initializes a rev_info on the
stack but never calls release_revisions() afterwards.  This is not
visible on master but becomes a leak once the revision walking
machinery uses dynamically allocated structures.

Add the missing release_revisions() call.

Signed-off-by: Kristofer Karlsson <krka@spotify.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/pack-objects.c

diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index 480cc0b..67025e8 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -4275,6 +4275,7 @@ static void enumerate_and_traverse_cruft_objects(struct string_list *fresh_packs
 	traverse_commit_list(&revs, show_cruft_commit, show_cruft_object, NULL);
 
 	stop_progress(&progress_state);
+	release_revisions(&revs);
 }
 
 static void read_cruft_objects(void)