There's a bit that's still lacking in Pip. For instance, Pip only installs new packages into your venv, rather than trying to keep it synchronized. I've run in

There's a bit that's still lacking in Pip. For instance, Pip only installs new packages into your venv, rather than trying to keep it synchronized. I've run into bugs where someone ripped a library out of requirements.txt because they thought it wasn't being used any longer. Turns out it was still being used, but the dev couldn't tell because the lib was still in their venv. Tools like Bundler will actually take the dependency away from you. Python's packaging system is great compared to C, but it's primitive compared to Ruby, Haskell, Clojure, and lots of others.