Possible unserialize() call for non-serialized value in menu_link_save()

function menu_link_save(&$item, $existing_item = array(), $parent_candidates = array()) {
  // …
  if (isset($item['mlid'])) {
    if (!$existing_item) {
      $existing_item = db_query('SELECT * FROM {menu_links} WHERE mlid = :mlid', array('mlid' => $item['mlid']))->fetchAssoc();
    }
    if ($existing_item) {
      $existing_item['options'] = unserialize($existing_item['options']);
    }
  }
  // …

If I pass in as the second parameter a menu item as loaded from menu_link_load(), with the options value already unserialized, "Warning: unserialize() expects parameter 1 to be string, array given in menu_link_save()" results. (It looks like it's not really necessary to pass in the menu item when updating it, but what the heck, it saves a redundant query.)

Unintentionally evil patch file size FTW.