$ git clone -n https://src.fedoraproject.org/rpms/OpenSceneGraph.git /var/lib/mock/f42-build-863161-171464/root/chroot_tmpdir/scmroot/OpenSceneGraph
Cloning into '/var/lib/mock/f42-build-863161-171464/root/chroot_tmpdir/scmroot/OpenSceneGraph'...
$ git fetch origin db58e608b1b1cc67df9ebfcf30e59e5ada141d3a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/OpenSceneGraph
 * [new ref]         db58e608b1b1cc67df9ebfcf30e59e5ada141d3a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at db58e60 Rebuild (openexr)