uses treeless fetches instead of `--depth`. This is not supported by
`actions/checkout`, so it was implemented as a short script (staying
with `actions/checkout@v1` does not seem like a good idea because of
its age, and updating to `actions/checkout@v3` would require adding
`libstdc++` to any CI workflows that run in void containers because
of node's requirements)
see also: https://github.blog/2020-12-21-get-up-to-speed-with-partial-clone-and-shallow-clone/
this can't be implemented as a script in `common/travis/` because the
repo doesn't exist on the runner (yet!)
also fix indentation in cycle check
From chroot-git 2.33.1, we always have an executable named git
for other build infrastructure and lints.
Let's remove the shenanegan to find which git to be used, prepend the
path to chroot-git's git into $PATH, and let's the shell call the
correct git for us instead.
