title: Checking out specific branch from github
body: <p>I used to pull down jQuery-ui by doing</p>
  
  <pre><code>git clone git://github.com/jquery/jquery-ui/
  git checkout 1.8.6
  </code></pre>
  
  <p>This stopped working today.  After I do a git clone on an empty repository, the checkout fails with: </p>
  
  <blockquote>
    <p>error: You have local changes to
    'demos/spinner/currency.html'; cannot
    switch branches.</p>
  </blockquote>
  
  <p>Any recommendations on how to fix this?  I don't want to pull zips of 1.8.6, I want the ease of being able to switch between old and new branches of jQuery UI for testing.</p>