message: refactor iterators per replica
diff: @@ -1760,7 +1760,6 @@ def _create_iterators_per_replica(input_contexts,input_workers,
  iterators = []
  for i, ctx in enumerate(input_contexts):
  devices = input_workers.compute_devices_for_worker(i)
  - with ops.device(devices[0]):
  dataset = dataset_fn(ctx)
  # Wrapping dataset here (ex. applying options) might result in moving it to the CPU
  iterator = _SingleReplicaDatasetIterator(dataset, devices[0])
  