"With Debian, of course, upgrading is just a matter of
changing to the next release in /etc/apt/sources.list and doing
aptitude dist-upgrade. With Ubuntu, that doesn't work out so
cleanly (though I can attest that it does work if you're willing to
hack around on it a bit). You have to use the do-release-upgrade
"So enough pointless rambling, how do we get do-release-upgrade
to recognize our local apt-mirror server? Do read on..."