Comment 3 for bug 1843076

This is indeed an issue introduced by the latest u-r-u changes. It it not a bug in ubuntu-release-upgrader code per-se though, it's all because of how weirdly update-manager uses the u-r-u code. It's astonishing that update-manager creates a MyCache class that inherits from DistUpgradeCache.MyCache but actually *does not* call its constructor, instead only initializing what the base apt.Cache constructor would do. I'm pretty sure this is done for some purpose, but it does feel like bad design to me. It relies on people knowing that such a thing is happening and trusting that all of the DistUpgradeCache.MyCache code that we use in update-manager will only rely on members initialized by apt.Cache. It just feels *so* wrong.

Anyway, I will try working around this in u-r-u, since otherwise I would have to backport both update-manager and ubuntu-release-upgrader to disco (instead of just one package).