[issue42775] __init_subclass__ should be called in __init__

[Ethan Furman]

Ethan Furman <ethan at stoneleaf.us> added the comment:

My understanding of using keywords in class headers

  class MyClass(SomeBaseClass, setting='maybe'):
    ...

is that the keywords would get passed into the super classes `__init_subclass__`  (`SomeBaseClass` and `setting`).

However, in the cases of 

- test_descr.py
- test_py_compile.py
- typing.py

that wasn't happening -- until the initial patch of moving the calls from `type.__new__` to `type.__init__`.

An `__init__` has been added in those three locations to discard the keyword arguments being passed in.

----------
nosy: +rhettinger, stutzbach

_______________________________________
Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue42775>
_______________________________________