Waitlist signup not working for full paid events

CiviCRM 4.4.x seems to have introduced a bug which does not allow participants to waitlist a full, paid event.

There is a thread on the topic: http://forum.civicrm.org/index.php/topic,30689.msg131591.html

The problem seems to come from the fact that the fee part of the form is still active, even when trying to waitlist.

Proposed patch at: https://github.com/civicrm/civicrm-core/pull/2641