In the container setup I created at work, VUnit is included as a submodule, and it is installed with python3 setup.py install inside the container. That creates build and dist directories inside the VUnit folder, which makes the submodule show untracked content. I include VUnit as a submodule in the repo, because it lets us keep track of which version of VUnit is used for the repo and decouples the version of VUnit from the container used for simulation.

I can get rid of build by running python3 setup.py clean --all after installation, but that still doesn't get rid of the dist folder.

For anyone else who has a similar problem but can't easily modify the submodule's .gitignore, you can add lines to the submodule info/exclude file inside the .git/modules/ folder.