Message 357903 - Python tracker

This is now fixed as a result of fixing bpo-16575. The unioncrash.py script now gives an error message:

$ python3.9 ~/tmp/unioncrash.py 
Traceback (most recent call last):
  File "/home/vinay/tmp/unioncrash.py", line 10, in <module>
    sin.argtypes = [MyUnion]
TypeError: item 1 in _argtypes_ passes a union by value, which is unsupported.