What version are you running?
2.5.3
What's the URL of the page containing the problem?
/r/#/diff/#-#/
What steps will reproduce the problem?

Create a review request with code changes
Create a new revision where a file only has whitespace changes from the previous revision
Open the interdiff between those revisions
Expand or collapse sections in the file


What is the expected output? What do you see instead?
When it expands or collapses, it does that fine.  However, it also creates a duplicate "This file contains only whitespace changes." line at the top of the file.  If you expand or collapse multiple times, you get one duplicate line added each time.
What operating system are you using? What browser?
Windows 7, Firefox
Please provide any additional information below.
I was going to attempt to recreate on the demo.reviewboard.org site to see if it is an issue in 3.0.  However, the demo site is currently erroring out with a "Something broke! (Error 500)" any time I try to log in...