CiviGroup Roles Sync: Can match incorrect user

The module looks up what user to assign a role to based on the email address of their Drupal account. This is not accurate enough, as there could be several users with that email address, in theory.

//find the contact record
    $params = array('version' => 3, 'sequential' => 1, 'email' => $user->mail );

$contact_id = CRM_Utils_Array::value( 'contact_id', $contact['values'][0] );

We need to use the actual contact ID associated with the Drupal user instead.