The attached scripts causes infinite recursion on the C level resulting in a
crash.
The script defines a subclass of object that throws an exception in its
__reduce__ method.
This method is then uses as the value of a slot on a subclass of float. This
subclass also defines a __class__ property that returns the __class__ of the
value in its sole slot.
Finally an instance of the subclass of float is pickled. This results in
infinite recursion. The problem goes away when __reduce__ doesn't raise
an exception or when the __class__ property is removed.