Matplotlib version: built from source after commit ba019f7 (8.11.2016)
Python version: 2.7.12 (built from source)
Platform: Ubuntu Linux 14.04

The following dialog with python interpreter demonstrates the problem I'm having:

from matplotlib.backends import _tkagg
Traceback (most recent call last):
File "", line 1, in
AttributeError: 'module' object has no attribute 'file'
_tkagg
Traceback (most recent call last):
File "", line 1, in
NameError: name '_tkagg' is not defined
from matplotlib.backends import _tkagg
_tkagg
<module 'matplotlib.backends._tkagg' (built-in)>

Here are the key points:

1. Python is not able to import matplotlib.backends._tkagg at first
2. When the import is tried the second time it is succesfull
3. The _tkagg is built-in module which I believe should not have 'file' attribute but at first Python would like to have it

Please advise.

Best Regards,

Eelis