$ git clone -n https://src.fedoraproject.org/rpms/rust-lab.git /var/lib/mock/f38-build-side-43-rust-devel-1417013-31458/root/chroot_tmpdir/scmroot/rust-lab
Cloning into '/var/lib/mock/f38-build-side-43-rust-devel-1417013-31458/root/chroot_tmpdir/scmroot/rust-lab'...
$ git fetch origin b141fe52ca4f90761b0f6b32641c8fb3a6150b2a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-lab
 * [new ref]         b141fe52ca4f90761b0f6b32641c8fb3a6150b2a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b141fe5 Regenerate with rust2rpm v24