- Fixed regression where we apparently still create an implicit

- Fixed regression where we apparently still create an implicit
alias when saying query(B).join(B.cs), where "C" is a joined inh
class; however, this implicit alias was created only considering
the immediate left side, and not a longer chain of joins along different
joined-inh subclasses of the same base.   As long as we're still
implicitly aliasing in this case, the behavior is dialed back a bit
so that it will alias the right side in a wider variety of cases.
[ticket:2903]