Preferred Language reset after editing contact

When a contact's communication preferences group of fields are edited, the preferred language of the contact is changed to the default language (set at admin/setting/localization), which will be saved, replacing the the previous value the contact may have.

On the demo server:

go to Administer->Localisations->Languages, Currency, Locations

set the default language to Catalan;Valencian (in my case)

Go to a contact (on the Demo site, Jed Adams, for example)

Edit communications preferences.

The preferred language Combo Box is set to Catalan;Valencian, rather than the language the contact had previously set.

Saving the contact with a different preferred language, and then reediting, gives the same result.

I've just tried this setting the site (CiviCRM) default language to English (British), and the same thing happens (A contact with preferred language English (US)), will have the Combo Box value initialised to English (British) when edited.

I posted this on the CiviCrm Community forums(http://forum.civicrm.org/index.php/topic,30930.msg132727.html#msg132727)