Actually, while I do still think this is an apt bug, I've found a workaround in ubiquity which doesn't seem too unreasonable; the effect will be that any corrupted downloads will be removed and the entire set of packages currently attempting to be installed will be skipped; that will normally mean language packs don't get installed, which is not ideal but not a showstopper. I think that will be enough to let me take this off the rls-p-tracking list.
Actually, while I do still think this is an apt bug, I've found a workaround in ubiquity which doesn't seem too unreasonable; the effect will be that any corrupted downloads will be removed and the entire set of packages currently attempting to be installed will be skipped; that will normally mean language packs don't get installed, which is not ideal but not a showstopper. I think that will be enough to let me take this off the rls-p-tracking list.