AttributeError with pip install matplotlib - python-2.7

Question

I am attempting to install matplotlib with pip inside a virtualenv on Ubuntu Linux. I already have a bunch of packages installed successfully - this is the one that's failing. As the output indicates, This is python 2.7.3 and all of the dependencies are already present.
Is this specific to v1.4.3 of matplotlib? Should I perhaps install an earlier version? I've even manually installed mock (v1.3.0), since the install seems to fail on trying to import it, but that didn't help either.
Here is the output:
Collecting matplotlib
Using cached matplotlib-1.4.3.tar.gz
Complete output from command python setup.py egg_info:
============================================================================
Edit setup.cfg to change the build options
BUILDING MATPLOTLIB
matplotlib: yes [1.4.3]
python: yes [2.7.3 (default, Jun 22 2015, 19:33:41) [GCC
4.6.3]]
platform: yes [linux2]
REQUIRED DEPENDENCIES AND EXTENSIONS
numpy: yes [version 1.9.2]
six: yes [using six version 1.9.0]
dateutil: yes [using dateutil version 2.4.2]
pytz: yes [using pytz version 2015.4]
tornado: yes [tornado was not found. It is required for the
WebAgg backend. pip/easy_install may attempt to
install it after matplotlib.]
pyparsing: yes [using pyparsing version 2.0.3]
pycxx: yes [Couldn't import. Using local copy.]
libagg: yes [pkg-config information for 'libagg' could not
be found. Using local copy.]
freetype: yes [version 2.4.8]
png: yes [version 1.2.46]
qhull: yes [pkg-config information for 'qhull' could not be
found. Using local copy.]
OPTIONAL SUBPACKAGES
sample_data: yes [installing]
toolkits: yes [installing]
Traceback (most recent call last):
File "<string>", line 20, in <module>
File "/tmp/pip-build-mHyI6G/matplotlib/setup.py", line 155, in <module>
result = package.check()
File "setupext.py", line 666, in check
import mock
File "/home/awarnock/PyProjects/OMTO3dIMG/local/lib/python2.7/site-packages/mock/__init__.py", line 2, in <module>
import mock.mock as _mock
File "/home/awarnock/PyProjects/OMTO3dIMG/local/lib/python2.7/site-packages/mock/mock.py", line 71, in <module>
_v = VersionInfo('mock').semantic_version()
AttributeError: 'VersionInfo' object has no attribute 'semantic_version'
----------------------------------------
Command "python setup.py egg_info" failed with error code 1 in /tmp/pip- build-mHyI6G/matplotlib
Thanks in advance for any suggestions.

Answer 1

You can try with:
pip install oslo.utils
Or:
pip install testrepository
pip install oslo.utils
You can also install it with packages:
Debian / Ubuntu:
apt-get install python-matplotlib
Redhat / CentOS:
yum install python-matplotlib