$ git clone -n https://src.fedoraproject.org/rpms/kf6-purpose.git /var/lib/mock/f42-build-862298-170718/root/chroot_tmpdir/scmroot/kf6-purpose
Cloning into '/var/lib/mock/f42-build-862298-170718/root/chroot_tmpdir/scmroot/kf6-purpose'...
$ git fetch origin 75b8e3340ed694c9a6188b3b08500b6a4d5590c1:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/kf6-purpose
 * [new ref]         75b8e3340ed694c9a6188b3b08500b6a4d5590c1 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 75b8e33 6.8.0