Do not automatically update git checkout with refs
I had to commit https://gitlab.gnome.org/GNOME/gnome-build-meta/commit/8340e0130a1c6f59388385f55b2b55e493e00dec today to remove some refs that I had accidentally committed. It's inevitable that mistakes like these will occur so long as BuildStream is storing refs -- something that we only want to be kept locally -- inside the git checkout of the project. BuildStream should never automatically edit files that are kept under version control. I would expect local changes to be kept under ~/.local/data/buildstream or someplace else instead.