Novell Access Management 3.1 Support Pack 3 applied
As a result a HTTP/1.1 404 Not Found was received.
They had forward received hostname configured while the hostname of the back-end webserver was the same as the defined dns name of the accelerator.
When setting the alternate hostname instead of forwarding the received hostname the rewriting was working again.
Reported to engineering. In this case there should not be a need to set the alternate hostname for rewriting to work