[PyQt] small emit bug

[Peter Shinners]

I think I've found a small bug in the bindings to QObject.emit. If there 
is an error raising the signal, the Python interpreter gets an error 
set, but the C code does not return NULL.

Python eventually picks up on the error a random number of instructions 
later. Just browsing the qobject.sip I can't be sure if this is the 
problem or not, but I recognize these symptoms from my own bindings.

The specific exception I'm seeing is,
TypeError: Signal has 0 arguments, but 1 given