pacman-key: reject armored signatures

pacman expects an unarmored signature.  makepkg forces the generation of
unarmored signatures, and repo-add will reject any armored signature.
For consistency pacman-key should also reject armored signatures.

Signed-off-by: Allan McRae <allan@archlinux.org>

scripts/pacman-key.sh.in

@@ -483,6 +483,10 @@ verify_sig() {
 	local ret=0
 	for sig; do
 		msg "Checking %s..." "$sig"
+		if grep -q 'BEGIN PGP SIGNATURE' "$sig"; then
+			error "$(gettext "Cannot use armored signatures for packages: %s")" "$sig"
+			return 1
+		fi
 		if ! "${GPG_PACMAN[@]}" --status-fd 1 --verify "$sig" | grep -qE '^\[GNUPG:\] TRUST_(FULLY|ULTIMATE).*$'; then
 			error "$(gettext "The signature identified by %s could not be verified.")" "$sig"
 			ret=1