$edit variable in user_mailman_register_user_delet

This function gives an error when called from a Migrate rollback (and possibly elsewhere; I haven't checked) because the $edit variable does not exist.

/**
* Implements hook_user_delete()
*/
function user_mailman_register_user_delete($account) {
_user_mailman_register_subscribe($account, $edit, TRUE);
db_delete('mailman_users')
->condition('uid', $account->uid)
->execute();
}

Editing the second line to read:
_user_mailman_register_subscribe($account, $edit = NULL, TRUE);
prevents the error.