see https://github.com/pypa/pip/commit/d051a00fc57037104fca85ad8ebf2cdbd1e32d24#diff-058e40cb3a9ea705f655937e48f3a053f5dc7c500b7f1b2aae76e9bd673faf64 scratch scratch over https://github.com/winpython/winpython/blob/master/winpython/wppm.py#L381-L384
