Apparently I haven’t gone mad, and the security fixes announced in this and this announcement do not, for all intents and purposes, actually exist for end users at the moment (bug 31584 and bug 31585).
Malone (the Launchpad bugtracker now used by Ubuntu) must have improved since I last used it. I remember way back when every time I filed a bug against something else I would have to file four bugs against Malone itself. Now I’m down to a one-to-one ratio (bug 31581 and bug 31583) plus a couple more nitpicks (bug 31586 and bug 31621). This is still much more frustration than I’m really happy with: I spent literally an hour trying to report that those security updates were missing, and it was only as small as that because I’m one of the twenty people in the world who live with a Launchpad developer. Alas, since I use Ubuntu and need to give them feedback on my problems if I want my computers to keep working, they have me all locked up on this one. And I normally find bug scutwork soothing in small amounts…