title: virtualenv uses Python 2.6 instead of 2.7
body: <p>I created a virtualenv and installed some packages with pip.  I want to use Python 2.7, which is the default version on my system.
  The env's lib folder contains a folder for Python 2.6, not 2.7.  Why is it not using 2.7, and how can I correct it?</p>
  
  <pre class="lang-none prettyprint-override"><code>$ python -V
  Python 2.7.6
  
  $ virtualenv flask
  
  flask/
      bin/
      app/
      lib/
         Python2.6/
  </code></pre>