Merge branch 'jk/is-promisor-object-keep-tree-in-use' into maint

An earlier optimization discarded a tree-object buffer that is
still in use, which has been corrected.

* jk/is-promisor-object-keep-tree-in-use:
  is_promisor_object(): fix use-after-free of tree buffer

packfile.c

@@ -2229,7 +2229,17 @@ static int add_promisor_object(const struct object_id *oid,
 			       void *set_)
 {
 	struct oidset *set = set_;
-	struct object *obj = parse_object(the_repository, oid);
+	struct object *obj;
+	int we_parsed_object;
+
+	obj = lookup_object(the_repository, oid);
+	if (obj && obj->parsed) {
+		we_parsed_object = 0;
+	} else {
+		we_parsed_object = 1;
+		obj = parse_object(the_repository, oid);
+	}
+
 	if (!obj)
 		return 1;
 
@@ -2251,7 +2261,8 @@ static int add_promisor_object(const struct object_id *oid,
 			return 0;
 		while (tree_entry_gently(&desc, &entry))
 			oidset_insert(set, &entry.oid);
-		free_tree_buffer(tree);
+		if (we_parsed_object)
+			free_tree_buffer(tree);
 	} else if (obj->type == OBJ_COMMIT) {
 		struct commit *commit = (struct commit *) obj;
 		struct commit_list *parents = commit->parents;

t/t5616-partial-clone.sh

@@ -49,6 +49,13 @@ test_expect_success 'do partial clone 1' '
 	test "$(git -C pc1 config --local remote.origin.partialclonefilter)" = "blob:none"
 '
 
+test_expect_success 'rev-list --missing=allow-promisor on partial clone' '
+	git -C pc1 rev-list --objects --missing=allow-promisor HEAD >actual &&
+	git -C pc1 rev-list --objects --missing=print HEAD >expect.raw &&
+	grep -v "^?" expect.raw >expect &&
+	test_cmp expect actual
+'
+
 test_expect_success 'verify that .promisor file contains refs fetched' '
 	ls pc1/.git/objects/pack/pack-*.promisor >promisorlist &&
 	test_line_count = 1 promisorlist &&