add test for reading variable-length array by itself
add test for reading variable-length array by itself

scikit-hep/root_numpy,rootpy/root_numpy,ndawe/root_numpy,rootpy/root_numpy,scikit-hep/root_numpy,ndawe/root_numpy,scikit-hep/root_numpy,ndawe/root_numpy,rootpy/root_numpy,rootpy/root_numpy,scikit-hep/root_numpy,ndawe/root_numpy