title: Import Tensor flow library error
body: <p>After debugging, I found that below strange error</p>
  
  <p>Program: (only 1 line)
  import tensorflow as tf</p>
  
  <p>When I run above code first time, I got below warning:
  \AppData\Local\Continuum\anaconda3\lib\site-packages\h5py__init__.py:36: FutureWarning: Conversion of the second argument of issubdtype from <code>float</code> to <code>np.floating</code> is deprecated. In future, it will be treated as <code>np.float64 == np.dtype(float).type</code>.
    from ._conv import register_converters as _register_converters</p>
  
  <p>=> From web, this is just an warning and can ignore it ( i guess)</p>
  
  <p>When I rerun the same code, I got below error</p>
  
  <p>File "C:\Users\AppData\Local\Continuum\anaconda3\lib\site-packages\spyder\utils\site\sitecustomize.py", line 710, in runfile
      execfile(filename, namespace)</p>
  
  <p>File "C:\Users\AppData\Local\Continuum\anaconda3\lib\site-packages\spyder\utils\site\sitecustomize.py", line 101, in execfile
      exec(compile(f.read(), filename, 'exec'), namespace)</p>
  
  <p>File "H:/Python/Test/Test.py", line 15, in 
      import tensorflow as tf</p>
  
  <p>File "C:\Users\AppData\Roaming\Python\Python36\site-packages\tensorflow__init__.py", line 24, in 
      from tensorflow.python import pywrap_tensorflow  # pylint: disable=unused-import</p>
  
  <p>File "C:\Users\AppData\Roaming\Python\Python36\site-packages\tensorflow\python__init__.py", line 121, in 
      from tensorflow.python.platform import test</p>
  
  <p>File "C:\Users\AppData\Roaming\Python\Python36\site-packages\tensorflow\python\platform\test.py", line 65, in 
      tf_export('test.mock')(mock)</p>
  
  <p>File "C:\Users\AppData\Roaming\Python\Python36\site-packages\tensorflow\python\util\tf_export.py", line 96, in <strong>call</strong>
      (undecorated_func.<strong>name</strong>, undecorated_func._tf_api_names))</p>
  
  <p>SymbolAlreadyExposedError: Symbol unittest.mock is already exposed as ('test.mock',).</p>
  
  <p>Now I need to restart the kernel in order to run through the whole source code.  Any idea ?</p>
  
  <p>Thanks</p>