$ git clone -n https://src.fedoraproject.org/rpms/rust-below.git /var/lib/mock/f40-build-1910102-25079/root/chroot_tmpdir/scmroot/rust-below
Cloning into '/var/lib/mock/f40-build-1910102-25079/root/chroot_tmpdir/scmroot/rust-below'...
$ git fetch origin 62c00588805a8711930801e0dacbb5713a73968e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-below
 * [new ref]         62c00588805a8711930801e0dacbb5713a73968e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 62c0058 Update to 0.8.1 (rhbz#2273710)