title: ImportError: cannot import name rewriter_config_pb2
body: <p>I am simply following the tutorials of tensorflow and while performing following cmd :</p>
  
  <pre><code>python ptb_word_lm.py --data_path=/home/priyankit/data/validsrc2-hi --
  model=small
  </code></pre>
  
  <p>It is showing following error:</p>
  
  <pre><code>Traceback (most recent call last):
  File "ptb_word_lm.py", line 68, in 
  import util
  File "/home/priyankit/models-master/tutorials/rnn/ptb/util.py", line 
  23, in 
  from tensorflow.core.protobuf import rewriter_config_pb2
  ImportError: cannot import name rewriter_config_pb2
  </code></pre>
  
  <p><a href="https://github.com/tensorflow/models/tree/master/tutorials/rnn/ptb" rel="nofollow noreferrer">link to the repository</a></p>