Comment 1 for bug 611182

wgrant on IRC says this is because I'm not a reviewer for that branch. It's true, but I am the submitter, and more importantly I am the person driving the work on this change, so I ought to be able to withdraw my proposal from review. If I'm considered fit to propose a change, I should also be considered fit to revoke that when I find the change is no longer appropriate for whatever reason. (In this case because a different merge proposal has effectively superseded it, but it's easy to imagine other cases.)