Due to an influx of spam, we have had to temporarily disable account registrations. Please write an email to firstname.lastname@example.org, with your desired username, if you want to get access. Sorry for the inconvenience.
If the keyring is not specified, pacman-key will simply use all keyrings from /usr/share/pacman/keyrings/.
See also archiso!174 (merged) & archlinux-docker!65 (merged).