$ git clone -n https://src.fedoraproject.org/rpms/kf5-knewstuff.git /var/lib/mock/f39-build-1540626-36477/root/chroot_tmpdir/scmroot/kf5-knewstuff
Cloning into '/var/lib/mock/f39-build-1540626-36477/root/chroot_tmpdir/scmroot/kf5-knewstuff'...
$ git fetch origin 87ed906ed8f6afd4e4fc4b894d71fe8ac8af141c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/kf5-knewstuff
 * [new ref]         87ed906ed8f6afd4e4fc4b894d71fe8ac8af141c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 87ed906 5.111.0