How do I turn off etckeeper. It's preventing me from upgrading Ubuntu
The hook should be in /etc/apt/apt.conf.d/05etckeeper. Moving it away should let you disable it.
However, it does not seem that it should prevent upgrades. What sort of error do you get?
I think the problem is with AVOID_COMMIT_BEFORE_INSTALL in /etc/etckeeper/etckeeper.conf. If set to 1 then do-release-upgrade will fail. I re-commented that line and all was fine.