RSS date is invalid when site is not in english

Last update of Drupal changed the way RSS date was generated to use format_date() instead of date(). This is a good improvement to honor timezones.

The problem is that the website is in Spanish (I suppose that in other languages that is a problem too), RSS date is cretaed in spanish and so, not valid.

If the RSS of your site is included in a planet or similar, then your feed dates are invalid and shown above the other.

The only solution I have ound is change format_date() by date() again, like this:

file: modules/node.module
line: 1925

$extra = array_merge($extra, array(array('key' => 'pubDate', 'value' => date('r', $item->created)), array('key' => 'dc:creator', 'value' => $item->name), array('key' => 'guid', 'value' => $item->nid .' at '. $base_url, 'attributes' => array('isPermaLink' => 'false'))));