Setting PYTHONPATH and PYTHONHOME using Heroku

I'm trying to set my PYTHONPATH and PYTHONHOME variables but can't figure it out!

When trying to run python, I get the error No module named site.

After doing some research, it seems that this is because these PYTHONPATH and PYTHONHOME environment variables are not set correctly.

When I try to run python after unsetting both of these variables, it is able to run properly. But the problem is that this only lasts for the life of my virtualenv. After I stop the virtualenv and run it again, the problem comes back.

Well I'm saying virtualenv, but really it's my environment on Heroku.

How do I unset these variables permanently?

Update: I followed the tutorial here which seemed to do the trick.