Dideved - 12:51 am on May 13, 2013 (gmt 0)
Thanks Dideved - I don't know how you found that out -- I spent ages trying/changing the htaccess file trying to get it to work!
I started off just copy-pasting your htaccess and tried a URL with a colon. Got a "Forbidden" response, which is unusual. Checked the error.log and saw the message "The given path is misformatted or contained invalid characters." Popped that error message into Google, and found the bug report I posted above.