$ git clone -n https://src.fedoraproject.org/rpms/systemd.git /var/lib/mock/f42-build-side-1-3573399-46767/root/chroot_tmpdir/scmroot/systemd
Cloning into '/var/lib/mock/f42-build-side-1-3573399-46767/root/chroot_tmpdir/scmroot/systemd'...
$ git fetch origin dae92c11b6a0c07a6087fe7235467fdd19ccc518:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/systemd
 * [new ref]         dae92c11b6a0c07a6087fe7235467fdd19ccc518 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at dae92c1 Version 257.6