title: Tensorflow successfully installs on mac but gets ImportError on copyreg when used
body: <p>After successfully <code>pip install</code>, importing the tensorflow library fails.</p>
  
  <pre><code>&gt;&gt;&gt; import tensorflow
  Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
    File "/Library/Python/2.7/site-packages/tensorflow/__init__.py", line 4, in &lt;module&gt;
      from tensorflow.python import *
    File "/Library/Python/2.7/site-packages/tensorflow/python/__init__.py", line 13, in &lt;module&gt;
      from tensorflow.core.framework.graph_pb2 import *
    File "/Library/Python/2.7/site-packages/tensorflow/core/framework/graph_pb2.py", line 8, in &lt;module&gt;
      from google.protobuf import reflection as _reflection
    File "/Library/Python/2.7/site-packages/google/protobuf/reflection.py", line 58, in &lt;module&gt;
      from google.protobuf.internal import python_message as message_impl
    File "/Library/Python/2.7/site-packages/google/protobuf/internal/python_message.py", line 59, in &lt;module&gt;
      import six.moves.copyreg as copyreg
  ImportError: No module named copyreg
  </code></pre>