On Python 2.7.11, pickle.whichmodule(object.__new__, None) = 'email.MIMEAudio'

This is unlikely to be the correct module.

I get other result:

>>> import pickle
>>> pickle.whichmodule(object.__new__, None)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/serhiy/py/cpython2.7/Lib/pickle.py", line 823, in whichmodule
    if name != '__main__' and getattr(module, funcname, None) is func:
TypeError: getattr(): attribute name must be string

Could you please provide the full example?

Ah, I get the same result as you in a clean interpreter session. Looks like it's not Python's fault.

The bug seems to arise from an interaction with cloudpickle 0.2.1 (and only in IPython), which puts the bad value into a cache somewhere in the pickle module.

So I'll take this issue to cloudpickle. 



In [1]: import cloudpickle

In [2]: cloudpickle.dumps(object.__new__)
Out[2]: '\x80\x02cemail.MIMEAudio\n__new__\nq\x00.'

In [3]: import pickle

In [4]: pickle.whichmodule(object.__new__, None)
Out[4]: 'email.MIMEAudio'