Actually you've misread it or I didn't explain it well enough :) A private library/app can have abstract dependencies. As I said in the post it deals with the

Actually you've misread it or I didn't explain it well enough :) A private library/app can have abstract dependencies. As I said in the post it deals with the "deploy specific" side of a Python application. So each specific deployment would get it's own requirements.txt. And yes requirements.txt is a pip only thing but the concept applies to the similar file in zc.buildout whose name escapes me at the moment and any other similar file.