if (commit->maybe_tree || !commit->object.parsed)
                return commit->maybe_tree;
 
-       if (commit->graph_pos == COMMIT_NOT_FROM_GRAPH)
-               BUG("commit has NULL tree, but was not loaded from commit-graph");
+       if (commit->graph_pos != COMMIT_NOT_FROM_GRAPH)
+               return get_commit_tree_in_graph(r, commit);
 
-       return get_commit_tree_in_graph(r, commit);
+       return NULL;
 }
 
 struct object_id *get_commit_tree_oid(const struct commit *commit)
        item->date = parse_commit_date(bufptr, tail);
 
        if (check_graph)
-               load_commit_graph_info(the_repository, item);
+               load_commit_graph_info(r, item);
 
        return 0;
 }