debian ships a modified site.py which has some interesting behavior when
VIRTUAL_ENV is set. In this case it will add
/usr/lib/pythonx.x/site-packages to the start of sys.path. This causes
pip to install packages to this location (rather than /usr/local). As a
result, later on when booting where VIRTUAL_ENV is not set this branch
is not hit and the path where python packages were installed is not part
of sys.path.
Change-Id: Icdb769541eee9793f261b4b8ec563be76ee13fe2
54b2733ad8