Manually remove Python package on Heroku

I've had problems where Heroku caches broken packages and there's no way to get them out. The Python buildpack should have some kind of support for flushing this cache (CACHE_DIR), but it does not.

There is a workaround: follow these instructions to change your Python runtime to, for instance, 3.3.0 (it doesn't matter if your app actually supports Python 3 or not). Then change it back to the default. The act of changing your Python runtime and then deploying will force the buildpack to totally erase the cache. As far as I know this is the only practical way to erase the cache at the moment.