views_handler_filter_in_operator::get_value_options treats $value_options incorrectly

  function get_value_options() {
    if (isset($this->value_options)) {
      return;
    }

...

This seems to be simply wrong.
Why return undefined when there is data to return?
Perhaps the following should be more appropriate?

  function get_value_options() {
    if (isset($this->value_options)) {
      return $this->value_options;
    }

...