Setting enable_weakrefs on a subclass of a class that also does it is broken

[MatthieuDartiailh]

The typical traceback is:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
    import platform
    ^^^^^^^^^^^^^^^
    import sys
    ^^^^^^
  File "C:\Users\DartiailhMatthieu\Documents\Coding\Projects\atom\atom\meta\atom_meta.py", line 557, in __new__  
    return helper.create_class(meta)
           ~~~~~~~~~~~~~~~~~~~^^^^^^
  File "C:\Users\DartiailhMatthieu\Documents\Coding\Projects\atom\atom\meta\atom_meta.py", line 495, in create_class
    cls: type = type.__new__(meta, self.name, self.bases, self.dct)
                ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: __weakref__ slot disallowed: we already got one