DatabaseStatementPrefetch.fetchAll() implementation does not work when $fetch_style parameter is PDO::FETCH_CLASS

Other users are experiencing this same bug: drupal.org/node/1565384
When using ->fetchAll() method like this:

$query->fetchAll(PDO::FETCH_CLASS, 'my_class_name');

the second parameter ($fetch_column) is the class name of objects returned into result array.

Actual DatabaseStatementPrefetch.fetchAll() implementation does not work like this, and second parameter is simply ignored (it works only for PDO::FETCH_COLUMN mode).

File /includes/database/prefetch.inc, line 425:

  public function fetchAll($fetch_style = NULL, $fetch_column = NULL, $constructor_args = NULL) {
    $this->fetchStyle = isset($fetch_style) ? $fetch_style : $this->defaultFetchStyle;
    $this->fetchOptions = $this->defaultFetchOptions;
    if (isset($fetch_column)) {
      $this->fetchOptions['column'] = $fetch_column;
    }
   //...

should read:

  public function fetchAll($fetch_style = NULL, $fetch_column = NULL, $constructor_args = NULL) {
    $this->fetchStyle = isset($fetch_style) ? $fetch_style : $this->defaultFetchStyle;
    $this->fetchOptions = $this->defaultFetchOptions;
    if (isset($fetch_column)) {
      if ($fetch_style & PDO::FETCH_COLUMN) {
          $this->fetchOptions['column'] = $fetch_column;
      } else if ($fetch_style & PDO::FETCH_CLASS){
          $this->fetchOptions['class'] = $fetch_column;
      }
    }
   //...

This bug appeared on my side after installing the i18n_strings module, and it prevents nodes deletion.
Function i18n_string_load_multiple in i18n_string.inc(456) calls fetchAll with PDO::FETCH_CLASS parameter, and should return an array of 'i18n_string_object' classes, but returns stdClass instead.
I think this bug is related to Drupal core and not i18n project, because the latter calls ->fetchAll() correctly (but it doesn't work as expected):

// file /sites/all/modules/i18n/i18n_string/i18n_string.inc
return $query->execute()->fetchAll(PDO::FETCH_CLASS, 'i18n_string_object');

The attached patch fixes the bug.