[3.7] bpo-36953: Delay removal of ABCs from collections. (GH-13409) by miss-islington · Pull Request #16675 · python/cpython
Bump the removal to 3.9, indicate collections.abc available since 3.3,
replace version-changed directive to deprecated-removed.
https://bugs.python.org/issue36953
(cherry picked from commit eea47e0)
Co-authored-by: Matthias Bussonnier mbussonnier@ucmerced.edu