Comment 2 for bug 429689

mvo: since it will be impossible for update-manager to proceed in this situation, at that point can't it just redownload the indexes, reanalysis the download situation and try again (a second, or even third round will be much progressively quicker since it's only indexes any remaining files).

...I think it should be safe to do this as it's only at the stage of downloading .debs and has not started the actual installation part

There didn't seem to be an obvious way to force update-manager that it should *ignore8 its cached idea of what might be on the servers. What determines how long update-manager keeps its cache of the next-distro indexes for?