Thanks!

We experienced that exact same pain. Whether it's pip or Bundler, I can't tell you how many times I've installed and reinstalled requirements.

Sharing data volumes is kind of a hack to make it really easy to keep part of a container around when you delete and recreate a container. I would love to see persistent data volumes become first class citizens so you don't have to create a separate container for them.

For now, though, it's saved us from having to put everything directly into the image in development.