message: Small fix to MultiDeviceIterator to allow for no prefetching if needed.
diff: @@ -633,6 +633,15 @@ class MultiDeviceIterator(object):
  devices,
  prefetch_buffer_size=1,
  source_device="/cpu:0"):
  + """Constructs a MultiDeviceIterator.
  +
  + Args:
  + dataset: The input dataset to be iterated over.
  + devices: The list of devices to fetch data to.
  + prefetch_buffer_size: if > 1, then we setup a buffer on each device
  + to prefetch into.
  + source_device: The host device to place the `dataset` on.
  + """
  self._dataset = dataset
  self._devices = devices
  self._source_device = source_device
  @@ -673,6 +682,7 @@ class MultiDeviceIterator(object):
  i, self._multi_device_iterator_resource, self._incarnation_id,
  self._source_device_tensor, device, self._dataset.output_shapes,
  self._dataset.output_types, self._dataset.output_classes)
  + if prefetch_buffer_size > 0:
  ds = ds.prefetch(prefetch_buffer_size)
  with ops.device(device):
  self._device_iterators.append(ds.make_initializable_iterator())
  