Dupe matching overrides profile fields with null values in lieu of filling

This issue is related to CRM-2124 fixed in CiviCRM 1.8.

If someone donates via contribution page (likely true for events and subscription profiles) that has a profile exposed the profile field overwrites the value in CiviCRM with the one on the exposed profile in the record that is matched in CiviCRM. This occurs even if the field on the submitted profile is null, therefore overriding the value in CiviCRM with null even if the field has a value.

This only occurs in Drupal set-ups (I'm not sure if Joomla has a similar concept) on contribution page when users settings are set to "Only site administrators can create new user accounts." And again only when CiviCRM determines the the newly entered ecord is a match with one already in CiviCRM.