In comment #13 I said that creating /etc/update-manager/release-upgrades.d/DistUpgrade.cfg allowed me to work around the problem. It looks like this approach has at least one major problem:
On a system that has a variety of PPAs configured, if I do the aforementioned "AllowThirdParty = true" hack, these PPA sources all get rewritten to use precise instead of lucid. If any PPA no longer exists in Precise, the upgrade fails.
The old behavior was smart enough to rewrite just the sources for the local mirror, and disable the rest.
In comment #13 I said that creating /etc/update- manager/ release- upgrades. d/DistUpgrade. cfg allowed me to work around the problem. It looks like this approach has at least one major problem:
On a system that has a variety of PPAs configured, if I do the aforementioned "AllowThirdParty = true" hack, these PPA sources all get rewritten to use precise instead of lucid. If any PPA no longer exists in Precise, the upgrade fails.
The old behavior was smart enough to rewrite just the sources for the local mirror, and disable the rest.