mailing list subscriptions pages do not apply form rules for previous subscription when addressed directly with 'gid='

Mailing list subscription pages do not apply a check for previous subscription status when using "gid="

To recreate on demo server:
1. Visit http://drupal.demo.civicrm.org/civicrm/mailing/subscribe&gid=2&reset=1
2. Subscribe with a new email address. See the message "Your subscription request has been submitted. Check your inbox shortly for the confirmation email(s)."
3. Revisit http://drupal.demo.civicrm.org/civicrm/mailing/subscribe&gid=2&reset=1
4. Enter the same email address as in step 2, and see the same message "Your subscription request has been submitted. Check your inbox shortly for the confirmation email(s)."

Desired behaviour:
A check on existing subscription status should be applied, and at step 4, the message should be: "You are already subscribed in Advisory Board, your subscription is Pending."