title: pytest requires Python '>=3.5' but the running Python is 2.7.10
body: <p>I'm trying to install <code>pytest</code> using <code>pip</code> but running into this error:</p>
  
  <pre><code>pytest requires Python '&gt;=3.5' but the running Python is 2.7.10
  </code></pre>
  
  <p>Pretty sure <code>pytest</code> is compatible with python 2. Any reason why I am not able to install it on my machine? As you can see in the error, I am running python 2.7.10 and do not have issue installing other packages.</p>