Additional users not registered to event with "Offer a wait list" when event payment (pay later) is associated

I set this up on http://drupal.demo.civicrm.org.

Create an event with 2 as maximum number of participants.

Select the "Offer a wait list" check button.

Make this a paid event, with "Enable Pay Later option?" selected.

Register two participants.

The attempt to register a third participant, doesn't get past the confirmation page, as shown in the attachment.

If the fee is removed, the addition of participants to the waiting list works fine.

[Actually looking at the status, I now realise that this is not trivial, as Pending from pay later, and Pending from Wait List are on the same status attribute]

Many thanks,

Michael.