[PyQt] PyQt5 QThread parent argument

[David Cortesi]

The rest of the story:

It turns out that the Wing IDE version 5.0 (which is itself
based on Qt5) has some sort of wrapper around
QThread that somehow leaked into their debug execution
environment and caused the problem when user code
invoked the parent class with super().__init__.

They have given me a workaround and
the issue will be fixed in the next release, 5.0.3.