Resolve "pkg_resources has no attribute packaging"

- problem described here "pypa/pip#2679"

.travis.yml

@@ -5,6 +5,9 @@ before_install:
     - sudo touch /usr/share/pyshared/pykickstart/__init__.py
     - export PYTHONPATH=${PYTHONPATH}:/usr/share/pyshared/
     - python -c "import sys; print sys.path"
+    - tree /home/travis/virtualenv/python2.7.12/lib/python2.7/site-packages/pkg_resources
+    - python -c "import pkg_resources; pkg_resources.__file__"
+    - sudo find /home/travis/virtualenv/python2.7.12/lib/python2.7/site-packages/pkg_resources/ -name "*.pyc" -type f -delete
     - sudo ls -la /usr/share/pyshared/pykickstart/
 install: pip install tox
 script: