I think that is a fair alternative, but restoring the backup means that the repository is in a bit of a weird state. Whereas a bundle can be cloned from nicely. Your way does have the property that it includes hooks and config, though (which could be desired or not).

This is also non-deterministic between versions of tar, but I guess for this usecase that would be fine. It’s just not good for reproducible build systems when trying to recreate tarballs after years.

Does not meet stated goal of the author:

> The naive solution of simply backing up the entire file-system tree is clearly not desirable since that would clutter the backup with useless build artifacts.

Build artifacts can be filtered out with tar --exclude patterns, but this is a language-dependent set that will require curation.