Remove mypy: strict-optional=False from base_command.py.
Remove mypy: strict-optional=False from base_command.py.

pradyunsg/pip,pfmoore/pip,pypa/pip,pfmoore/pip,sbidoul/pip,pypa/pip,rouge8/pip,rouge8/pip,sbidoul/pip,pradyunsg/pip,xavfernandez/pip,xavfernandez/pip,xavfernandez/pip,rouge8/pip