Comment 7 for bug 672964

This is not a regression, but it is a latent bug that you were unlucky enough to hit. Something (it's not clear what) ran update-initramfs while udev was unconfigured; there are quite a few candidates and it's not clear exactly what did it. It probably doesn't matter.

I think it would be best for udev's initramfs hook to check whether /sbin/udevadm.upgrade exists. If it does, it should copy that into the initramfs as /sbin/udevadm, rather than the /sbin/udevadm wrapper script.