The following python program causes cpython to crash:

class A:
  global __class__
  def a(self):
    super()

I get the following output on the console:

bug.py:2: SyntaxWarning: name '__class__' is assigned to before global declaration
  global __class__
lookup '__class__' in � a sequ 2 -1
freevars of A: ('__class__',)
Fatal Python error: compiler_make_closure()

Current thread 0x00007fc712192700:
Aborted (core dumped)

This probably happens because __class__ is handled specially by the scoping rules and isn't expected to be anything other than a member of co_cellvars. It should probably throw an exception instead (SystemError?)