Comment 2 for bug 527245

I might implement this the way I always planned to in the past but never got around to (drilling down through the uninstallable stack until I find something I can actually dep-wait on). I have code locally that DTRT (or used to, a few years ago), just need to dust it off and sanely plug it into sbuild. No guarantees on timeframe here, but I'm hacking lp-buildd in the first months or two of the new year, so if this doesn't end up taking me much time, I might jam it in for "free".