`SparseSeries.shape` seems to return incorrect result ignoring shapes filled by `fill_value`. ``` s = pd.SparseSeries([0, 0, 1, 0], fill_value=0) s #0 0 #1 0 #2 1 #3 0 # dtype: int64 # BlockIndex # Block locations: array([2], dtype=int32) # Block lengths: array([1], dtype=int32) len(s) #4 # must be (4, )? s.shape # (1,) # OK s._data.shape # (4,) ```