title: Pyvenv cannot create virtual environment
body: <p>Usually I use <code>virtualenv</code> for python2.x. After some bitter experience with <code>unicode</code> encoding/decoding clash, I decided to upgrade to 3.x, But I can't create a virtualenv using pyvenv.</p>
  
  <pre><code>$ pyvenv-3.4 env
  Error: Command '['/home/user/delete_this/env/bin/python3.4', '-Im', 'ensurepip', '--upgrade', '--default-pip']' returned non-zero exit status 1
  </code></pre>
  
  <p>Also I'd be grateful if someone points to a good virtual environment for python3.x since I see a lot of options.</p>