check return value from parse_commit() in various functions

Signed-off-by: Martin Koegler <mkoegler@auto.tuwien.ac.at>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

commit.c

@@ -387,8 +387,7 @@ struct commit *pop_most_recent_commit(struct commit_list **list,
 
 	while (parents) {
 		struct commit *commit = parents->item;
-		parse_commit(commit);
-		if (!(commit->object.flags & mark)) {
+		if (!parse_commit(commit) && !(commit->object.flags & mark)) {
 			commit->object.flags |= mark;
 			insert_by_date(commit, list);
 		}

shallow.c

@@ -70,7 +70,8 @@ struct commit_list *get_shallow_commits(struct object_array *heads, int depth,
 				cur_depth = *(int *)commit->util;
 			}
 		}
-		parse_commit(commit);
+		if (parse_commit(commit))
+			die("invalid commit");
 		commit->object.flags |= not_shallow_flag;
 		cur_depth++;
 		for (p = commit->parents, commit = NULL; p; p = p->next) {

upload-pack.c

@@ -533,7 +533,8 @@ static void receive_needs(void)
 				/* make sure the real parents are parsed */
 				unregister_shallow(object->sha1);
 				object->parsed = 0;
-				parse_commit((struct commit *)object);
+				if (parse_commit((struct commit *)object))
+					die("invalid commit");
 				parents = ((struct commit *)object)->parents;
 				while (parents) {
 					add_object_array(&parents->item->object,