Compatibility with drupal7 image derivate token protection

Drupal 7.20 introduces a new concept of image derivate query string to deal with this security issue:
http://drupal.org/SA-CORE-2013-002

The security fixes in this release change all image derivative URLs generated by Drupal to append a token as a query string. ("Image derivatives" are copies of images which the Drupal Image module automatically creates based on configured image styles; for example, thumbnail, medium, large, etc.)

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

We need to make this compatible with stage file proxy :)

Scenario:

Drupal 7.20+

Request a nonexistent image on local server: /sites/default/files/styles/custom_style/public/images/myimage.jpg?itok=GgsLCDrQ

Stage file proxy handles it, on 200 response code it downloads the original image from the origin and moves to the local folder.

Refresh the request and let the web server work out the mime type, etc.

In the last step the module does not sends the itok query parameter and the petition gets a 403 response.

While this issue be solved you can set this on your settings.php:

$conf['image_allow_insecure_derivatives'] = TRUE;