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I realise that there are lots of things that you can do to
prevent or confuse introspection working in the pickle
module.  You can dynamically create classes on the fly too.
 It just seems a shame that it is possible to prevent the
most basic of class definitions from working in the pickler.

I can program around the problem but it took the better part
of a day to work out why I was experiencing the problem.

Maybe the correct bug fix is not to change code but to
improve the documentation of the pickle module.