title: Undigested Asset links in Rails 4.1 css.sass file
body: <p>I recently upgrade from rails 3.2 to rails 4.1.
  In my <code>user.css.sass</code> file I have</p>
  
  <pre><code>#profile
    background: image-url('icon_user.png')
  </code></pre>
  
  <p>Now when I run <code>rake assets:precompile</code> I expect to find a digested link in the user.css file, but I have </p>
  
  <pre><code>#profile{background:url(/assets/icon_user.png)};
  </code></pre>
  
  <p>This used work as rails produced undigested asset files along the ones with digests.
  How can I fix this issue?</p>