Thumbnails are not working in IE if images do not match extension

Steps to Reproduce

1. Create a new page
2. Attach an image with different mime type. For example: image/x-citrix-pjpeg.
3. If you don't have an image with that mime type, just attach any image and change the mime type to image/x-citrix-pjpeg. You can do this by going to Tools > Attachments > Properties
4. Display the image as a thumbnail

Expected Results

The image is displayed as expected and when clicking the image to zoom in, it will show the larger version. This works in both Firefox and Chrome.

Actual Results

The image is not displayed and the message "The requested content cannot be loaded. Please try again later." is shown when clicking on the image

Environment Information

IE 8 and IE 9

Workaround

1. Backup your Confluence database
2. Run a SQL query to change the MIME type of all images in the database. For example:

This query changes all images with MIME TYPE image/x-citrix-pjpeg to image/jpeg

UPDATE ATTACHMENTS SET CONTENTTYPE = 'image/jpeg' WHERE CONTENTTYPE = 'image/x-citrix-pjpeg';

This query changes all images with MIME TYPE image/x-citrix-gif to image/gif

UPDATE ATTACHMENTS SET CONTENTTYPE = 'image/gif' WHERE CONTENTTYPE = 'image/x-citrix-gif';