Broken delete port button in billing

In rev 7231, the delete port in bill edition seems broken.

Clicking on it generates links like:
.../bill/bill_id=9/view=edit/?action=delete_bill_port&port_id=947

Replacing ? and & with slashes actually make the action work.

It seems that there are bogus <form> imbrications in the page, and a tag open/close mismatch is shown in Firefox for example.