title: Using different versions of python with virtualenvwrapper
body: <p>I've got various versions of python installed on my Mac using Macports. When I've selected python 2.7 via <code>$ port select python python27</code>, virtualenvwrapper works perfectly. </p>
  
  <p>But if I select another version of python, i.e. 2.6, virtualenvwrapper generates an error message: ImportError: No module named virtualenvwrapper.hook_loader</p>
  
  <p>I checked my .profile and it's setting <code>VIRTUALENVWRAPPER_PYTHON</code> to <code>/opt/local/bin/python</code>, so it seems to me virtualenvwrapper should work regardless of which python I've selected.</p>
  
  <p>Any idea what would cause virtualenvwrapper to generate a .hook_loader error when I switch python versions?</p>