title: How to downgrade the installed version of 'pip' on windows?
body: <p>On a windows 7 machine I have <code>pip</code> version 1.5.6 installed:</p>
  
  <pre><code>pip 1.5.6 from C:\Users\dietz\PNC\tas\ENV\lib\site-packages (python 2.7)
  </code></pre>
  
  <p>In order to find the reason for an error I want to install a different version of pip, which worked fine for me. So how can I uninstall <code>pip</code> and install version 1.2.1 instead?</p>