$ git clone -n https://src.fedoraproject.org/rpms/rust-below-model.git /var/lib/mock/f40-build-1538303-23931/root/chroot_tmpdir/scmroot/rust-below-model
Cloning into '/var/lib/mock/f40-build-1538303-23931/root/chroot_tmpdir/scmroot/rust-below-model'...
$ git fetch origin a4c173e0c9bebf59bece6478d738ff3ac28c413e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-below-model
 * [new ref]         a4c173e0c9bebf59bece6478d738ff3ac28c413e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a4c173e Update to 0.8.1 (rhbz#2272252)