Ah, I see what's going on.  The revision of the socket code (nice job,
by the way) removed the distinction between the C socket object and the
Python socket object.  The C SSLContext keeps a pointer to the C socket
object, which is now the Python socket object, or in the SSL case, the
SSLSocket object.  So there's a circular reference.

The right fix is to make the ref in the SSL C code a weakref.