[issue40443] Remove unused imports in the stdlib (April 2020 edition)

[STINNER Victor]

Change by STINNER Victor <vstinner at python.org>:


----------
pull_requests: +19126
pull_request: https://github.com/python/cpython/pull/19805

_______________________________________
Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue40443>
_______________________________________