External domains form action failure

Domain Access does not handle properly external domains. For example, a payment module (Webmoney and Roboxchange are tested) for Ubercart forms an external link and the domain of that link is substituted by the current domain.
The error is there:
domain.module

function domain_form_alter($form_id, &$form) {
  // If SEO is turned on, then form actions need to be absolute paths
  // to the currently active domain.  See http://drupal.org/node/196217.
  $seo = variable_get('domain_seo', 0);
  if ($seo) {
    global $_domain;
    $action = parse_url($form['#action']);
    if ($action['query']) {
      $action['path'] .= '?';
    }
    $form['#action'] =  $_domain['scheme'] .'://'. $_domain['subdomain'] . $action['path'] . $action['query'];
  }

This code must be substituted by more correct:

function domain_form_alter($form_id, &$form) {
  // If SEO is turned on, then form actions need to be absolute paths
  // to the currently active domain.  See http://drupal.org/node/196217.
  $seo = variable_get('domain_seo', 0);
  if ($seo) {
    global $_domain;
    $action = parse_url($form['#action']);
    if ($action['query']) {
      $action['path'] .= '?';
    }
    if(empty($action["scheme"]) || empty($action["host"])){
        $form['#action'] =  $_domain['scheme'] .'://'. $_domain['subdomain'] . $action['path'] . $action['query'];
    }
  }