email address does not get copied into contact record when a match is made but email is not in the dedupe rule + patch

I have a load of imported user data with no email addresses, and a dedupe rule that doesn't involve the email at all. This means that when a user signs up via drupal, the new account matches an existing one and the contact record is correctly linked, but the email address is not copied over into the contact record.

To solve this, I altered /drupal/civicrm.module to update the email address when new user data is registered as per the attached patch