bpo-38979: fix ContextVar "__class_getitem__" method (GH-17497)


now contextvars.ContextVar "__class_getitem__" method returns ContextVar class, not None.

https://bugs.python.org/issue38979

Automerge-Triggered-By: @asvetlov
(cherry picked from commit 28c91631c24e53713ad0e8a2bbae716373f5e53d)

Co-authored-by: AMIR <31338382+amiremohamadi@users.noreply.github.com>
3 files changed