$ git clone -n https://src.fedoraproject.org/rpms/kf5-purpose.git /var/lib/mock/f38-build-729645-101821/root/chroot_tmpdir/scmroot/kf5-purpose
Cloning into '/var/lib/mock/f38-build-729645-101821/root/chroot_tmpdir/scmroot/kf5-purpose'...
$ git fetch origin 515d4663f0df4881cab99d73c11e3cdfa0ff7fa1:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/kf5-purpose
 * [new ref]         515d4663f0df4881cab99d73c11e3cdfa0ff7fa1 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 515d466 5.107.0