$ git clone -n https://src.fedoraproject.org/rpms/systemd.git /var/lib/mock/f42-build-864912-172636/root/chroot_tmpdir/scmroot/systemd
Cloning into '/var/lib/mock/f42-build-864912-172636/root/chroot_tmpdir/scmroot/systemd'...
$ git fetch origin 62abb21906759fba1b2120456843329fd9c7423e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/systemd
 * [new ref]         62abb21906759fba1b2120456843329fd9c7423e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 62abb21 Version 257.1