Remove _ipy reference to the InteractiveShell object again.

IPython/core/interactiveshell.py

@@ -29,7 +29,6 b' import re'
 import sys
 import tempfile
 import types
-from weakref import proxy
 
 try:
     from contextlib import nested
@@ -1058,7 +1057,6 b' class InteractiveShell(SingletonConfigurable, Magic):'
 
         # Store myself as the public api!!!
         ns['get_ipython'] = self.get_ipython
-        ns['_ipy'] = proxy(self)   # Weak ref since this is a circular reference
         
         ns['exit'] = self.exiter
         ns['quit'] = self.exiter