message: Re-prefetch the dataset for V1Adapater
diff: @@ -1959,6 +1959,9 @@ def _split_dataset_batch(dataset, split_batch_by):
  prefetch_buffer = None
  if isinstance(dataset, dataset_ops.PrefetchDataset):
  prefetch_buffer = dataset._buffer_size
  + elif (isinstance(dataset, dataset_ops.DatasetV1Adapter)
  + and isinstance(dataset._dataset, dataset_ops.PrefetchDataset)):
  + prefetch_buffer = dataset._dataset._buffer_size
  # pylint: enable=protected-access
  if tensor_util.is_tensor(batch_size):
  