$ git clone -n https://src.fedoraproject.org/rpms/kf6-knewstuff.git /var/lib/mock/f42-build-side-1-3586572-46923/root/chroot_tmpdir/scmroot/kf6-knewstuff
Cloning into '/var/lib/mock/f42-build-side-1-3586572-46923/root/chroot_tmpdir/scmroot/kf6-knewstuff'...
$ git fetch origin 4bbf2bce2ef246cd094243261fd3409593ebf794:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/kf6-knewstuff
 * [new ref]         4bbf2bce2ef246cd094243261fd3409593ebf794 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4bbf2bc 6.16.0