"container" images using FDo's ci-templates are built in a chroot with
different paths, breaking absolute paths and making us have to rely on
nobody ever using `cd` or `pushd` anywhere (since we also source every
script instead of executing them). Very fragile and I hate it, but it
hasn't been fixed yet so here we are.
Fixes: 675fe92e78 ("ci: read the MSRV from clippy.toml to avoid having too many copies to keep in sync")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/39055>
14b7340bbf