title: Tensorflow import error after building from source
body: <p>I built tensorflow with GPU support from source from this release <a href="https://github.com/tensorflow/tensorflow/releases/tag/v1.13.0-rc0" rel="nofollow noreferrer">https://github.com/tensorflow/tensorflow/releases/tag/v1.13.0-rc0</a> and everything worked without issue however when I imported tensorflow in python I get the errors</p>
  
  <pre><code>&gt;&gt;&gt; import tensorflow
  ImportError: No module named _multiarray_umath
  ImportError: No module named _multiarray_umath
  ImportError: numpy.core._multiarray_umath failed to import
  ImportError: numpy.core.umath failed to import
  Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
    File "tensorflow/__init__.py", line 24, in &lt;module&gt;
      from tensorflow.python import pywrap_tensorflow  # pylint: disable=unused-import
    File "tensorflow/python/__init__.py", line 52, in &lt;module&gt;
      from tensorflow.core.framework.graph_pb2 import *
    File "tensorflow/core/framework/graph_pb2.py", line 6, in &lt;module&gt;
      from google.protobuf import descriptor as _descriptor
  ImportError: No module named protobuf
  </code></pre>
  
  <p>I do have protobuf installed.  Also I an using ubuntu 16.04 with CUDA 10. Doe anyone know what the problem is here?</p>