Advanced search by gender (or any other field in demographics) does not retain its values on POST

When the interface is localised to another language (multi-lingual or simply localised), we can't use the advanced search to create a smart group for a specific gender.

For example:

• set localisation -> language to another language, such as French
• go to advanced search, search by Demographics->Gender = Female (or choose any other field)
• create a smart group with the results
• view smart group contacts: it will be empty.

While debugging, all I could find is that in CRM/Contact/Form/Task/SaveSearch.php postProcess(), doing:
dsm($this->get('formValues'));

shows that the value for gender is an empty string.

Issue originally reported on the forum: http://forum.civicrm.org/index.php/topic,27706.0.html