commit-reach: plug minor memory leak after using is_descendant_of()

ref_newer() builds a commit_list to pass a single potential ancestor to
is_descendant_of().  The latter leaves the list intact.  Release the
allocated memory after the call.

Signed-off-by: René Scharfe <l.s.r@web.de>
Acked-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

commit-reach.c

@@ -396,6 +396,7 @@ int ref_newer(const struct object_id *new_oid, const struct object_id *old_oid)
 	struct object *o;
 	struct commit *old_commit, *new_commit;
 	struct commit_list *old_commit_list = NULL;
+	int ret;
 
 	/*
 	 * Both new_commit and old_commit must be commit-ish and new_commit is descendant of
@@ -417,7 +418,9 @@ int ref_newer(const struct object_id *new_oid, const struct object_id *old_oid)
 		return 0;
 
 	commit_list_insert(old_commit, &old_commit_list);
-	return is_descendant_of(new_commit, old_commit_list);
+	ret = is_descendant_of(new_commit, old_commit_list);
+	free_commit_list(old_commit_list);
+	return ret;
 }
 
 /*