title: Upgrade python without breaking yum
body: <p>I recently installed Python 2.7.3 on a CentOS machine by compiling from source. Python 2.7.3 is installed at /opt/python2.7 and when I installed it I just changed /usr/bin/python to point to the new version. This apparently is wrong though because when I did it it broke yum. I would get the following.</p>
  
  <pre><code>There was a problem importing one of the Python modules
  required to run yum. The error leading to this problem was:
  
     No module named yum
  
  Please install a package which provides this module, or
  verify that the module is installed correctly.
  
  It's possible that the above module doesn't match the
  current version of Python, which is:
  2.7.3 (default, May 15 2012, 17:45:42) 
  [GCC 4.4.4 20100726 (Red Hat 4.4.4-13)]
  
  If you cannot solve this problem yourself, please go to 
  the yum faq at:
    http://yum.baseurl.org/wiki/Faq
  </code></pre>
  
  <p>I changed /usr/bin/python to point back to the python 2.6.6 but now 2.6.6 is the default version of python. Any idea how to fix this?</p>