Malformed URL getting library

Sometime over the weekend Bootswatch API starting returning https: for its urls. In template.php, that breaks the following:
        drupal_add_css($base['scheme'] . ":" . $css, 'external');

A workaround for me is:
      if (strpos($css, 'http') <> 0) {
        drupal_add_css($base['scheme'] . ":" . $css, 'external');
      }
      else {
        drupal_add_css($css, 'external');
      }
