Hey, I have wrote Pundle to solve this problem! Idea is simple — we just have package to install other packages with versions freeze. Pundle maintaine frozen.txt alongside with requirements.txt.

What more — pundle does not use virtualenv and install all packages to user directory ~/.Pundledir and import frozen versions on demand.

It have all nice commands like install, upgrade, info etc

Check it https://github.com/Deepwalker/pundler