When a module is garbage collected, it fills it's __dict__ with None.  issue19255 and issue18214 seem to suggest that this was fixed, along with github pull request 7140 (commit 196b0925ca55bf22ffbb97733cff3e63d4fb6e18).  However, this still seems to be an issue in 2.7.14 and 3.6.2.

>>> import sys
>>> a = type(sys)('a')
>>> b = a.__dict__
>>> b['__name__'] is None
False
>>> del a
>>> b['__name__'] is None
True

I cannot reproduce this in 3.6.5:

>>>import sys
>>>import gc
>>>a = type(sys)('a')
>>>b = a.__dict__
>>>print(b['__name__'] is None)
False
>>>del a
>>>gc.collect()
>>>print(b['__name__'] is None)
False


On the other hand, this still happens in 2.7.15:

Python 2.7.15 (default, May  1 2018, 20:16:04)
[GCC 7.3.1 20180406] on linux2
Type "help", "copyright", "credits" or "license" for more information.

>>>import sys
>>>import gc
>>>a = type(sys)('a')
>>>b = a.__dict__
>>>print(b['__name__'] is None)
False
>>>del a
>>>gc.collect()
>>>print(b['__name__'] is None)
True

I also can't reproduce it on a later version. If this is a 2.7/3.6 only problem, should the issue be closed?