title: conda install downgrade python version
body: <p>I'm trying to downgrade python version of anaconda via <code>conda install python=3.3</code>, but have following error:</p>
  
  <pre><code>~/anaconda3/bin$ ./conda install python=3.3
  Fetching package metadata .........
  Solving package specifications: .
  
  
  UnsatisfiableError: The following specifications were found to be in conflict:
    - gevent -&gt; python 2.6*
    - python 3.3*
  Use "conda info &lt;package&gt;" to see the dependencies for each package.
  </code></pre>
  
  <p>How to resolve conflicts with the packages?</p>