Unicode::isSimple() problem

Problem/Motivation

  public static function isSimple($string, $length = 250, $allowed_tags = NULL, &$html = FALSE) {
    ...
    if (!isset($strings[$string_clone])) {
      $plain_string = strip_tags($string_clone);
      $simple = TRUE;
      if ($allowed_tags !== FALSE) {
        $filtered_string = Xss::filter($string_clone, $allowed_tags);
        $html = $filtered_string !== $plain_string;
        ...
      }
      ...
    }
    ...
  }

So if isset($strings[$string_clone]) $html will not get a correct value.