message: create new iterator instance for each iter
diff: @@ -64,8 +64,8 @@ class DatasetBenchmarkBase(test.Benchmark):
  if context.executing_eagerly():
  deltas = []
  - iterator = iter(dataset)
  for _ in range(iters):
  + iterator = iter(dataset)
  if warmup:
  next(iterator)
  start = time.time()
  