$ git clone -n https://src.fedoraproject.org/rpms/kscreenlocker.git /var/lib/mock/f42-build-side-1-3583546-46889/root/chroot_tmpdir/scmroot/kscreenlocker
Cloning into '/var/lib/mock/f42-build-side-1-3583546-46889/root/chroot_tmpdir/scmroot/kscreenlocker'...
$ git fetch origin 3d1d21c96ebf2dbec219720d8452b2b694a8f42a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/kscreenlocker
 * [new ref]         3d1d21c96ebf2dbec219720d8452b2b694a8f42a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3d1d21c 6.4.2