title: Your PYTHONPATH points to a site-packages dir for Python 3.x but you are running Python 2.x
body: <p>I'm running on macOS 10.12, and I'm trying to install Django using: </p>
  
  <pre><code>pip install Django==1.10.5
  </code></pre>
  
  <p>I get this error:</p>
  
  <pre><code>Your PYTHONPATH points to a site-packages dir for Python 3.x but you are running Python 2.x!
   PYTHONPATH is currently: "/usr/local/lib/python3.6/site-packages:"
   You should `unset PYTHONPATH` to fix this.
  </code></pre>
  
  <p>I have Python3 and Python2.7 installed with macOS on my system, but I really only want to use Python3 for pretty much everything. Pretty new to using / configuring Python, has anyone else come across this?</p>