Need view of publishing history by DistroSeries

[William Grant]

With the advent of package copying, DistroSeries -changes lists are almost useless post-release, but there's no alternative. Once s-i-s is in place, they will be completely useless, and there will be no way to work out what updates have happened recently.

The publishing history for each DistroSeries (perhaps filterable by pocket, as most people don't care about -proposed) should be accessible somewhere.