title: Asset URLs without cache timestamps in Rails
body: <p>I'm using a transparent PNG with the <a href="http://code.google.com/p/ie7-js/" rel="nofollow noreferrer">Google IE fix</a> library. This fix only works on images urls that end in "-trans.png".</p>
  
  <p>Rails' timestamp-based caching is causing problems with this. When I use image_path() to generate the URL for the image, it appends the file's last-modified timestamp to the image's query string. Since the URL no longer ends in "-trans.png" (instead ending in "?" plus a long integer), Google's javascript fails to activate.</p>
  
  <p>I don't want to <a href="https://stackoverflow.com/questions/183017/removing-cache-busting-in-rails-production/185396#185396">disable asset caching entirely</a>; just on certain images. I also don't want to hardcode a relative URL to the root of the server. I want to use Rails to generate the URL correctly if the site is deployed to the server root or an (unknown) subdirectory. </p>
  
  <p>What options do I have?</p>