Comment 1 for bug 1208909

I wonder whether we would also need a way to force a delta update in case deltas get larger than a full (e.g. many images fail QA, then the accumulated delta from last good image to latest image to test is larger than full image).

In practice, we should generate deltas from scratch in daily-proposed so that it's always a single delta and should never be larger than a full image, but it might be a good option just in case.