WebSocket, skips parse_variables at times, why?

[Stephen R. van den Berg]

I'm currently implementing the Engine.IO (and possibly Socket.IO) protocol
in Pike (bidirectional realtime communication with JavaScript clients).

While doing so I noticed (to my dismay) that in WebSocket, I find the
following code snippet:

    protected int parse_variables() {
        if (has_index(request_headers, "sec-websocket-key"))
            return 0;
        return ::parse_variables();
    }

I.e. parse_variables() is skipped on real websocket connections.
What would be the reason why this is being skipped?
I need to parse the variables on the URL of the soon-to-be-upgraded
websocket connection; so it would be more convenient if it was handled
automatically.
-- 
Stephen.