Cannot uncheck checkbox fields in civicrm profiles

Hi

I have recently noticed a problem where checkbox fields cannot be unchecked in profiles. I have reproduced it on the civicrm demo sandbox here: http://drupal.demo.civicrm.org/user/2/edit/test - Once one of the fields has been saved as checked, unchecking it and saving will not clear the field in the database.

This appears to be because the browser does not send anything if a checkbox is unchecked - so civicrm needs to do some work on the php side to check for missing checkbox fields in the postdata and unset them.

Thanks