I think the URL should have been only http://bugzilla.redhat.com.
This is this way because at the moment there are currently a couple of other services such as rhcn, and hardware certification being hosted on this server> We are going to in the near future have hardware.redhat.com, rhcn.redhat.com, and bugzilla.redhat.com go to their respective directories automatically but until then bugzilla.redhat.com/bugzilla does the trick. Thanks.