message: This CL fixes a crash that happens when fitting in Keras without scipy sparse libraries being installed.
diff: @@ -365,6 +365,7 @@ def model_iteration(model,
  'pass shuffle="batch".')
  # Sparse to dense conversion.
  + if issparse is not None:
  for i in indices_for_conversion_to_dense:
  ins_batch[i] = ins_batch[i].toarray()
  