Optimization: inside subquery, do tableref.make_join(pl_only=True) if possible
Optimization: inside subquery, do tableref.make_join(pl_only=True) if possible

git-svn-id: cc65bc9ed7fa717314bc8890b6f123117eea230e@2073 698dff77-f410-0410-8918-cf622e150f36

ponyorm/pony,ponyorm/pony,gwecho/pony,ponyorm/pony,gwecho/pony,gwecho/pony,ponyorm/pony