No module named extern

Originally reported by: dusijun (Bitbucket: dusijun, GitHub: dusijun)

UBNTU 15.10

python --version
Python 2.7.10

sudo pip install pip -I

...successfully installed pip-8.1.0

sudo pip install setuptools

...Sucessfully ..... setuptools-20.2.2

OR

wget https://bootstrap.pypa.io/ez_setup.py -O - | sudo python

Problem:

and build something from source eg, the pip

sudo python setup.py install

(or pip install pyaudio or pip install protobuf)

#!shell

File "setup.py", line 6, in <module>
    from setuptools import setup, find_packages
  File "/usr/local/lib/python2.7/dist-packages/setuptools/__init__.py", line 11, in <module>
    from setuptools.extern.six.moves import filterfalse, map
  File "/usr/local/lib/python2.7/dist-packages/setuptools/extern/__init__.py", line 1, in <module>
    from pkg_resources.extern import VendorImporter
ImportError: No module named extern

• Bitbucket: https://bitbucket.org/pypa/setuptools/issue/514

Reproduce the failure with Python 2.7.10 using the reported setup.py install command. Start by reading setuptools/init.py and setuptools/extern/init.py, then trace the import of pkg_resources.extern; done means the source install completes without ImportError: No module named extern.