$ git clone -n https://src.fedoraproject.org/rpms/systemd.git /var/lib/mock/f42-build-side-1-3503841-45982/root/chroot_tmpdir/scmroot/systemd
Cloning into '/var/lib/mock/f42-build-side-1-3503841-45982/root/chroot_tmpdir/scmroot/systemd'...
$ git fetch origin fff5f18f9e57d91c20bdd7d42d92cabe35df3f7e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/systemd
 * [new ref]         fff5f18f9e57d91c20bdd7d42d92cabe35df3f7e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at fff5f18 Backport CI fix