I believe a failure to upgrade from N-2 to N should not block the N
release. The reason is limited resources, both for tests and for changes
to fix problems. These resources are more valuable applied to the N
release than to something two releases in the past.
If someone wants to test a release-skipping upgrade, fine. Report
problems? Sure. If someone wants to fix these problems, OK; if not, the
policy should be "Upgrade one release at a time. Release-skipping
upgrades may work, but are not guaranteed."
If "upgrade N-2 -> N-1" works, and "upgrade N-1 -> N" works,
N-2 -> N" also works, right? Maybe not, and I think it profligate to
insist we fix a broken two-release upgrade when two single-release
upgrades successfully reach the desired target. Document, do not block.
I may hold a minority opinion, but this seems like another call for QA to
do somebody else's job. Who should decide that release-skip upgrade is a