notifications_delete_subscriptions query bug for multiple conditions

  if ($conditions) {
    $index = 0;
    foreach ($conditions as $field => $value) {
      $alias = 'nf'. $index;
      $join[] = "INNER JOIN {notifications_fields} $alias ON n.sid = $alias.sid";
      $where[] = "$alias.field = '%s'";
      $where[] = "$alias.value = '%s'";
      $args[] = $field;
      $args[] = $value;
    }
  }

The variable $index is never incremented thereby leading to duplicate aliases. Patch attached.