title: Why does virtualenv effectively disable Python 3 tab-completion?
body: <p>When I create an python3 virtual-env, tab-completion (default with python3) does not work any more. Why is that?</p>
  
  <pre><code>virtualenv -p /usr/bin/python3 --system-site-packages ~/venv3.site
  . ~/venv3.site/bin/activate
  </code></pre>
  
  <p>Without <code>--system-site-packages</code> it has the same problem: no tab-completion. If I run <code>python3</code> without any virtual-env activated, tab-completion works.</p>