How to version control pi-gen customizations?

[cmorganBE]

It looks like build.sh has to run from the pi-gen directory. How does one version control their changes to pi-gen, the config file etc?

Is the approach to add pi-gen to a git repo as a submodule, then run a script to copy files from the git repo into the pi-gen subdirectory, then cd pi-gen and ./build-docker.sh?

An alternative idea would be to fork pi-gen and commit changes there but that seemed slightly less clean than the copying approach.

Is there a third better option?