Cannot debug generated scripts using ipython in Python 3.6

I used to be able to run commands like bin/python `which ipython` --pdb -- bin/bob ... to debug my scripts. Now after I have switched to Python 3.6 this fails with the following error:

AttributeError                            Traceback (most recent call last)
/remote/idiap.svm/user.active/amohammadi/git/deep/bin/bob in <module>()
     64   ]
     65 if sys.version_info[:2] >= (3, 6): #see: http://bugs.python.org/issue30167
---> 66   _hack = str(sys.modules['__main__'].__loader__.__module__)
     67   sys.modules['__main__'].__loader__.__module__ += '_'
     68 import site #initializes site properly

AttributeError: 'NoneType' object has no attribute '__module__'
> /remote/idiap.svm/user.active/amohammadi/git/deep/bin/bob(66)<module>()
     64   ]
     65 if sys.version_info[:2] >= (3, 6): #see: http://bugs.python.org/issue30167
---> 66   _hack = str(sys.modules['__main__'].__loader__.__module__)
     67   sys.modules['__main__'].__loader__.__module__ += '_'
     68 import site #initializes site properly

However when I run just bin/bob ... it works.