Comment 5 for bug 467275

Yeah, rereading that now, I see it's talking about uploading a source package from a different, non-Ubuntu, Debian-based distro (e.g. Debian unstable) and being able to manually tell it which Ubuntu suite (e.g. jaunty or karmic) to build it for. If you upload a source package that is for a particular Ubuntu suite, it'll use whatever's in changelog no matter what. That explains why the override wasn't working.