Someone just needs to talk to the Debian people about fixing this. Honestly, I thought this was fixed two years ago, but a friend of mine (one who works in the Cydia ecosystem, ironically), was complaining about diff updates a couple weeks ago, and it turns out it was not. I mostly outsourced "upstreaming to distributions" (as opposed to to projects) to a friend of mine who now works for RightScale, and so I never really gained for myself the right contacts in that beurocracy, but if no one else does I should probably get around to sending this suggestion to them...