$ git clone -n https://src.fedoraproject.org/rpms/rust-below.git /var/lib/mock/f38-build-side-43-rust-devel-1405130-31208/root/chroot_tmpdir/scmroot/rust-below
Cloning into '/var/lib/mock/f38-build-side-43-rust-devel-1405130-31208/root/chroot_tmpdir/scmroot/rust-below'...
$ git fetch origin b1746f1a24906c6c323a92df09b427f39d76b26a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-below
 * [new ref]         b1746f1a24906c6c323a92df09b427f39d76b26a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b1746f1 Update to 0.7.1