Comment 5 for bug 1271237

I discussed that with Michael Vogt. It seems that installing trusty's apt first is hard to revert if the upgrade can't be calculated after that, or the user wants to abort. For lucid → precise we used to backport the current apt (release-upgrader-apt), but that's a rather intrusive step. If we have an easy fix for that for precise proper, SRUing apt would be the best course.

I just tried to backport http://anonscm.debian.org/gitweb/?p=apt/apt.git;a=commitdiff;h=b4140ecf1 to our precise apt, which applies fairly well. But this alone introduces some regression, apt-get update or many of the tests then say

E: Problem parsing dependency Depends
E: Error occurred while processing python3-gnupg (NewVersion2)
E: Problem with MergeList /tmp/tmp.kzDn7m7XFL/rootdir/var/lib/apt/lists/_tmp_tmp.kzDn7m7XFL_aptarchive_dists_stable_main_binary-amd64_Packages
E: The package lists or status file could not be parsed or opened.

So this will require another backported patch to go along with this, if we want to go with the SRU route.