Inheriting from 'object' introduces cycled reference.

[Jason Orendorff]

Kerim Borchaev wrote:
> Subject: Inheriting from 'object' introduces cycled reference.
> Is it intended behavior?

Yes.  The cycle is caused by a weak back-reference from 'object'
to the subclass.  That weak reference is used to implement
the new __subclasses__() method that types now have.

Note that the cycle doesn't prevent types from being GC'd nicely.

## Jason Orendorff    http://www.jorendorff.com/