title: ImportError: No module named core.framework.graph_pb2
body: <p>When I follow the Installation for linux from <a href="http://www.tensorflow.org/get_started/os_setup.md" rel="nofollow noreferrer">tensorflow offical site</a>, everything is fine until the last step: <strong>Train your first TensorFlow neural net model</strong>. </p>
  
  <p>When I execute the command, <code>python tensorflow/models/image/mnist/convolutional.py</code>, An ImportError promps.</p>
  
  <pre class="lang-py prettyprint-override"><code>Traceback (most recent call last):
    File "tensorflow/models/image/mnist/convolutional.py", line 13, in &lt;module&gt;
      import tensorflow.python.platform
    File "/home/guo/haplox/Github/tensorflow/tensorflow/__init__.py", line 4, in &lt;module&gt;
      from tensorflow.python import *
    File "/home/guo/haplox/Github/tensorflow/tensorflow/python/__init__.py", line 13, in &lt;module&gt;
      from tensorflow.core.framework.graph_pb2 import *
  ImportError: No module named core.framework.graph_pb2
  </code></pre>
  
  <p>My OS is 14.04.1-Ubuntu.</p>