Another recent developer bug bear was the fact that Arch installs files to /lib instead of /usr/lib. This needed fixing, seriously, people were losing sleep over it.
So, that was fixed, in every single package, without Announcement.
How the hell are people that maintain AUR packages supposed to know? I know because I read the arch-dev-public mailing list (what doesn’t get auto binned that is).
This, as with the evil Udev symlinks, broke something too but since that only happened by chance, no-one seemed to think it was important.
It’s a simple “bug”: the Udev rules owned by device-mapper moved. As a result packages that used those udev rules when installing mkinitcpio hooks (like lvm2) got updated to point at the new location. Perfect.
However, the linux package rebuilds the initcpio immediately. If, like me, you got unlucky and lvm2 installed after linux then mkinitcpio ran a broken hook install file and didn’t create the initcpio file properly.
Re-running mkinitcpio -p linux once pacman has finished updating fixes the problem.
However, if you don’t scrutinize your pacman.log for such errors, you could easily miss this and have an unbootable system.
Tough shit for not paying attention is the official response.