hacking should conform with OS requirements

hacking did not make any assumption on which version of six is
installed, therefore hacking pulled in an incompatible six version,
making it impossible to run the tests.

fixes bug 1222706

Change-Id: Icd31caa93587614425036fc4c8d3cfd3a83b6b3c
(cherry picked from commit 664bc299fd4433f723a06933959c6774e53ae697)
Merge "hacking should conform with OS requirements" into 0.7.x