Today, the system worked! I received an email from a user asking if I could add support for custom status codes to Post Test Server and I was happy to oblige. So I have added a new parameter which can be passed in the URL called: status_code which causes the server to return a response with the header set to: HTTP/1.0 $status Custom Status (where $status is the value of status_code). Regardless of what code is requested the post will still be dumped in folder in the usual way.
To make it very clear, hitting this url:
will cause the server to respond with HTTP/1.0 650 Custom Status.