Please see the provided URL. You will notice that the diff is incorrectly rendered.
Original text changed in diff:
http://download.wikimedia.org/wikipedia/ar تحميل ويكيبيديا العربية
It was changed to be:
[http://download.wikimedia.org/arwiki تحميل ويكيبيديا العربية]
I noticed this using Firefox 2. IE 7 does not have this problem. Also note that this happens on an RTL wiki (arwiki).
Version: unspecified
Severity: enhancement
URL: http://ar.wikipedia.org/w/index.php?title=%D9%85%D8%B3%D8%AA%D8%AE%D8%AF%D9%85:%D9%85%D9%8A%D9%85%D9%88%D9%86%D9%8A&diff=prev&oldid=1549958