No anonymous user in User Reference Filter!

Hello,

I have a cck node with user reference field (not required) and I have a view listing all nodes with this field = 0 (anonymous). I found that I wasn't able to configure view in such way because filter values list box doesn't have anonymous user.
In _userreference_potential_references($field) function you had the following piece of code in 4.7:

  if (!$field['required']) {
    $users = array(0 => '');
  } else {
    $users = array();
  }

This is exaclty what I need in my situation. I found that you removed this code from 5.0 version. Am I missing something? How should I configure my view to list all nodes with user reference field equal to 0?

Thanks