Video Thumbnail formatter breaks with images stored on S3 due to security fix in Drupal core update 7.20

Drupal version 7.20 has a security fix to the core Image module that breaks image generation with the Video thumbnail formatter.

http://drupal.org/drupal-7.20-release-notes

To recreate:

* Add the video field to a content type
* Configure the field to set its "Upload destination of thumbnails" to "Amazon S3"
* Add a thumbnail to a video
* Create a view and add the "Content: Video" field.
* Choose "Formatter" to be "Video thumbnail"
* Choose a Video thumbnail style
* Preview the view
* Notice that the image is broken

In my case, the generated image url is http://www.designindaba.com/sites/default/files/styles/inner_sb_set/http... which gives an "Access Denied". If I remove the querystring, then the image shows fine.

A number of other modules have been patched. From http://drupal.org/drupal-7.20-release-notes

... any code which programmatically generates a link to an image derivative without using the standard image_style_url() API function will no longer work correctly if the image does not already exist in the file system ...

I haven't delved into the Video module code yet so I'm not sure exactly what the fix will be.