Steps to reproduce

1. Create an instance of a resource-like module, other than the mod_resource (File) itself. Any module declaring FEATURE_MOD_ARCHETYPE as MOD_ARCHETYPE_RESOURCE, such as the Book module, is affected (all but Label which is excluded from the overview page).
2. Embed an image into the Description (intro) field of the module.
3. Add the Activities block to the course
4. Click the Resources item in the block to get to the page course/resources.php for that course.

Expected behaviour

The image is displayed in the desciption

Actual behaviour

The image source URL is broken, being hard-coded to be owned by the mod_resource plugin.