postProcess hook doesn't fire when creating an event

If you create this hook:
function testhook_civicrm_postProcess($formName, &$form) {
if ($formName == 'CRM_Event_Form_ManageEvent_EventInfo')

{ throw new Exception("Inside ManageEvent_EventInfo post process."); }

}
You would expect that exception to get thrown if you go to 'Events -> New Event', fill out required fields and hit submit. It does not get fired. But if you go to the "Info and Settings" tab for an existing event and click on "Save" then it will get fired.

I've included a patch against 4.2.8 that fixes this.