[docs] [issue42675] Document changes made in bpo-42195

Dec. 18, 2020

      New submission from Ken Jin <kenjin4096@gmail.com>:

A whatsnew is probably needed as this change causes backwards incompatibility in some code working with Python 3.9.0 and 3.9.1. I think the patch for Python 3.9.2 should mention that a DeprecationWarning is emitted for some invalid use cases, which will eventually become a TypeError.

----------
assignee: docs@python
components: Documentation
messages: 383304
nosy: docs@python, gvanrossum, kj
priority: normal
severity: normal
status: open
title: Document changes made in bpo-42195
versions: Python 3.10, Python 3.9

_______________________________________
Python tracker <report@bugs.python.org>
<https://bugs.python.org/issue42675>
_______________________________________