Given your particular requirement of differentiation from user and sytem-wide modules given a certain package, I would recommend looking at setting up virtualenv to run all your code in an isolated environment (to quote the link):
sudo pip install virtualenv
(or, sudo easy_install virtualenv if you don’t use pip)
(or, easy_install --install-dir ~/site-packages/ virtualenv on a shared host)
mkdir ~/virtualenvs (a directory for your isolated environments)
virtualenv ~/virtualenvs/mysite.com --no-site-packages
(--no-site-packages isolates your environment from the main site-packages directory)
cd ~/virtualenvs/mysite.com/bin
source activate (activates your new environment)
This would help save the need for path injection.