title: python virtualenv ImportError with celery and billiard
body: <p>i am building a new amazon instance with python 2.7.10 as default.
  after i have ran my machine provisioning scripts and the moment of truth arrives, celery gave me an import so i debugged the problem to billard.</p>
  
  <p>the package appears to be in the correct path i.e.</p>
  
  <pre><code>sudo find -name "billiard"
  ./srv/ia-live/lib64/python2.7/dist-packages/billiard
  </code></pre>
  
  <p>where ia-live is the path of my virtualenv. checking the path in via python virtualenv executable</p>
  
  <pre><code>import sys
  sys.path
  
  ['',
   '/srv/ia-live/bin',
   '/srv/ia-live/src/django-devserver-redux-master',
   '/usr/lib/python2.7',
   '/srv/ia-live/local/lib64/python2.7/site-packages',
   '/srv/ia-live/local/lib/python2.7/site-packages',
   '/srv/ia-live/lib64/python2.7',
   '/srv/ia-live/lib/python2.7',
   '/srv/ia-live/lib64/python2.7/site-packages',
   '/srv/ia-live/lib/python2.7/site-packages',
   '/srv/ia-live/lib64/python2.7/lib-dynload',
   '/srv/ia-live/local/lib/python2.7/dist-packages',
   '/srv/ia-live/local/lib/python2.7/dist-packages',
   '/srv/ia-live/lib/python2.7/dist-packages',
   '/usr/lib64/python2.7',
   '/usr/lib/python2.7',
   '/srv/ia-live/local/lib/python2.7/dist-packages/IPython/extensions',
   '/home/ec2-user/.ipython']
  </code></pre>
  
  <p>which appears to be correct, but when i do</p>
  
  <pre><code>import billiard
  ImportError: No module named billiard
  </code></pre>
  
  <p>i don't understand why there could be problem</p>