a  test for what's breaking, plus a non-working fix for it...
shrugs
dial back the default "flatness" a bit, it will be there for joinedload and query.join(), but if
you're dealing with aliased() or with_polymorphic() you need to say "flat=True".  Just the one
flag though, "flat" implies "aliased".
Merge branch 'ticket_2587'