Why is pacman-key trying to download the public key for the Pacman Keyring Master Key?

Question

When running sudo pacman-key --refresh-keys I get the following message:

gpg: public key of ultimately trusted key XXXXXX not found

I could find only one reference to this key (sudo locate found nothing):

$ sudo grep -r XXXXXX /etc/
/etc/pacman.d/gnupg/openpgp-revocs.d/XXXXXX.rev:      XXXXXX

Having a look inside it seems this is the revocation certificate of some auto-generated key which only my machine knows about. What am I supposed to do now to make pacman-key sane?

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This also seems to be affecting the "checking keys in keyring" and "checking package integrity" phases of pacman -Syu, to the extent that a full core is 100% occupied with gpg or gpg2 indefinitely.

Answer 1

This plus this seem to have worked:

$ sudo rm -r /etc/pacman.d/gnupg
$ sudo pacman-key --init
$ sudo pacman-key --populate archlinux
$ sudo pacman -S archlinux-keyring