Well that certainly wasn't worth the amount of angst I'd pre-allocated it.
The upgrade went reasonably smoothly. Lowlights included:
- aptitude wanting to uninstall sendmail in favour of exim4. I think mailman was the culprit. I wasn't in the mood to get to the bottom of it, I just upgraded Sendmail first, then stuck it on hold, then Aptitude decided to upgrade Mailman as well, which is what makes me think it was Mailman
- inetd coming back from the dead. I probably removed all of the rcN.d links instead of just the start ones.
- gallery got upgraded on me despite it being on hold, so I had to scramble to repatch it afterwards to reenable friends.andrew.net.au
I'm certainly glad to be getting security updates again. Given how smoothly this went, I'll definitely not procrastinate on upgrading to Lenny when it releases.