Today I managed to get myself a little bit stuck with Heroku's otherwise seamless Python support. In an earlier revision of my app, I had used -e to install an editable version of a package (the version of the package I needed had not yet been released to PyPI, so I pointed pip at Github). Since then, the version I need has been released.

So, update requirements.txt, then git push heroku master, and all is well, right? Not so fast...