I recently upgrade my Drupal6 site to Drupal7 and migrated to getpantheon platform, I am hand-coding absolute image url's in nodes like this :
<div align="center"> <img src="http://www.megaleecher.net/sites/default/files/images/sneaksy.jpg" style="max-width:100%;height:auto" alt="sneaksy" /> </div>
Despite using full absolute url's, images in feedburner are getting broken :
http://feeds.feedburner.com/TheBestInternetNews as it's source
http://www.megaleecher.net/rss.xml is outputting relative images.
$base_url = 'http://megaleecher.net'; (without www) in settings.php fixes the issue but using
$base_url = 'http://www.megaleecher.net'; (with www) makes them relative again.
I have hired two drupal dev's from oDesk (https://www.odesk.com/o/jobs/job/Fixing-relative-image-paths-Drupal-rss-feed_~~0c48e61824bc3263/) and also asked for support from getpantheon but no solution.