$ git clone -n https://src.fedoraproject.org/rpms/flatpak-kcm.git /var/lib/mock/f42-build-3427178-45202/root/chroot_tmpdir/scmroot/flatpak-kcm
Cloning into '/var/lib/mock/f42-build-3427178-45202/root/chroot_tmpdir/scmroot/flatpak-kcm'...
$ git fetch origin b6726fd4cdb33afd8d38104df22b049dea56ac7b:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/flatpak-kcm
 * [new ref]         b6726fd4cdb33afd8d38104df22b049dea56ac7b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b6726fd 6.3.3