$ git clone -n https://src.fedoraproject.org/rpms/rust-tower-util.git /var/lib/mock/f41-build-side-1-2897358-34638/root/chroot_tmpdir/scmroot/rust-tower-util
Cloning into '/var/lib/mock/f41-build-side-1-2897358-34638/root/chroot_tmpdir/scmroot/rust-tower-util'...
$ git fetch origin 3a81e5c6911d879ba2b64b22ceb1442f37d1e5f6:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-tower-util
 * [new ref]         3a81e5c6911d879ba2b64b22ceb1442f37d1e5f6 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3a81e5c unused leaf package for more than two release cycles