Allow to import pip10's main from pip9's /usr/bin/pip
    
    Users are upgrading pip9 to pip10 by various manners,
    one of them is `pip install --user --upgrade pip`.
    
    If they do that and they run `pip` or  `pip3`, the one from /usr/bin is used.
    However that's the one from this RPM package (pip9) and the import in there
    fails (it tries to import from ~/.local, but pip10 is there with a bit
    different API).
    
    We add a patch as a dirty workaround to make /usr/bin/pip* work with
    both pip9 (from this RPM) and pip10 (from whatever).
    
    A proper fix is to put ~/.local/bin in front of /usr/bin in the PATH,
    however others are against that and we cannot change it for existing
    installs/user homes anyway.
    
    This is a workaround for:
     * https://bugzilla.redhat.com/show_bug.cgi?id=1569488
     * https://bugzilla.redhat.com/show_bug.cgi?id=1571650
    
    Patch is applied in %install, because /usr/bin/pip* are entrypoints.