Log Message:
give up supplementary group memberships on uid/gid switch, fixes
unexpected privileges reported in PR pkg/40532 by Cem Kayali,
the issue is being discussed with upstream,
thanks to Cem for detailed reports,
also back out explicit passing of PRIVOXY_GROUP to the program --
while it does not hurt it is redundant because PRIVOXY_GROUP is already
the primary group of PRIVOXY_USER