Same here on my forum... whether I put 1 / or 30 of 'em it just goes to the location requested, stripping out the "/".
For XenForo.com, it does give that trashed out page.
Let's blame it on Mike messing with the code on the support forum.
yep - confirmed using http://twowheeldemon.com//forum gives me an error page (my custom one). I used multiple '/' at the end and not before the /forum as I misunderstood what was being referred to.