title: subprocess.check_output doesnt work in python 3, but works in python 2.7
body: <p>I have the following code, which gave me correct results python 2.7, but as soon as I have ported to python 3, the code doesnt work as expected. I can see correct results in the variable <code>submodule_commit</code>, but they are like <code>b'xxxxxxx\nyyyyyyy'</code> and the split doesnt work anymore. 
  I dont understand, wht is going wrong here. 
  My expectations is a list with submodules.</p>
  
  <pre><code>command = "git submodule status | awk '{print $1}'"
  submodule_commit = subprocess.check_output(command, shell=True)
  submodule_commit = submodule_commit.split('\n')
  </code></pre>