bpo-36820: Break unnecessary cycle in socket.py, codeop.py and dyld.py (GH-13135)



Break cycle generated when saving an exception in socket.py, codeop.py and dyld.py as they keep alive not only the exception but user objects through the ``__traceback__`` attribute.


https://bugs.python.org/issue36820



Automerge-Triggered-By: @pablogsal
4 files changed