Fix #982 by using the effective user id on unix systems instead of depending on
getpass.getuser(). This is required because on some systems 'LOGNAME'
is not updated by sudo.
Signed-off-by: david <db@d1b.org>
Merge pull request #998 from d1b/fix_pip_location_sudo_usage

Fix #982 by using the effective user id on unix systems instead of depen...