[wyldfire]

I haven't really used requirements.txt because I found that I could install 'extra' and 'test' specific content based on args to setup() in my setup.py. It seems more like the Right Thing than requirements.txt, from what I can tell.

At first glance, this doesn't seem to offer anything beyond what I already see from setup(). What am I missing?

It's unfortunate that CPython gave us distutils and took a very long time to converge on a built-in successor (setuptools?) that gives the right composability.