[PyQt] sipConvertToInstance failing after sipCanConvertToInstance succeeds.

[Diez B. Roggisch]

> 
> I missed your call to sipFindClass().
> 
> It's almost certainly a bug in your handwritten code somewhere - not
> necessarily in the code above.


ok, I'm feeling stupid now. But after building sip with debug enabled, 
and stepping into the conversion-call, I found that the problem was that 
the error-variable I passed was *uninitialized*. There are reasons why I 
don't like c++ anymore...

You mention this behavior in the docs - but maybe an additional warning 
for idiots like me would be in order :)

Diez