[blog_estimators_dataset.py] bug fix for failing demo

[timmolter]

Here's the error I got before making this fix:

TensorFlow version: 1.5.0-rc0
Traceback (most recent call last):
  File "/Users/timmolter/workspaces/workspace_tf/models/samples/outreach/blogs/blog_estimators_dataset.py", line 86, in <module>
    next_batch = my_input_fn(FILE_TRAIN, True)  # Will return 32 random elements
  File "/Users/timmolter/workspaces/workspace_tf/models/samples/outreach/blogs/blog_estimators_dataset.py", line 76, in my_input_fn
    .map(decode_csv))  # Transform each elem by applying decode_csv fn
  File "/usr/local/lib/python3.6/site-packages/tensorflow/python/data/ops/dataset_ops.py", line 780, in map
    return MapDataset(self, map_func)
  File "/usr/local/lib/python3.6/site-packages/tensorflow/python/data/ops/dataset_ops.py", line 1583, in __init__
    self._map_func.add_to_graph(ops.get_default_graph())
  File "/usr/local/lib/python3.6/site-packages/tensorflow/python/framework/function.py", line 486, in add_to_graph
    self._create_definition_if_needed()
  File "/usr/local/lib/python3.6/site-packages/tensorflow/python/framework/function.py", line 321, in _create_definition_if_needed
    self._create_definition_if_needed_impl()
  File "/usr/local/lib/python3.6/site-packages/tensorflow/python/framework/function.py", line 338, in _create_definition_if_needed_impl
    outputs = self._func(*inputs)
  File "/usr/local/lib/python3.6/site-packages/tensorflow/python/data/ops/dataset_ops.py", line 1571, in tf_map_func
    ret, [t.get_shape() for t in nest.flatten(ret)])
  File "/usr/local/lib/python3.6/site-packages/tensorflow/python/data/ops/dataset_ops.py", line 1571, in <listcomp>
    ret, [t.get_shape() for t in nest.flatten(ret)])
AttributeError: 'list' object has no attribute 'get_shape'

[tensorflow-jenkins]

Can one of the admins verify this patch?

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[timmolter]

I signed it!

[googlebot]

CLAs look good, thanks!

[MarkDaoust]

Thanks. I've confirmed that this fixes the problem.