TL;DR: Wait until I push 20120522 later today, and run `librechroot clean-repo` to fix your chroot, or delete it and recreate it.

I've just fixed it in git. I'll push 20120522 by the end of the day (more bugs to squash!).

I was about to explain why this was confusing because the fix is to run `pacman -Sy` after adding [repo], but before running pacman again, but that it does this! It turns out that `pacman -Sy` was failing because /repo/repo.db didn't exist yet. I've added creating an empty repo.db to the create action.

`librechroot clean-repo` will also "fix" a chroot because it rm's the file and re-creates it. I've just added `mkdir /repo` to it for the case that the directory doesn't exist.

Actually, prior to 20130528.1, it failed to create a necessary simlink. The rest of my above post still applies.