Install archlinux-keyring and archlinuxarm-keyring

The dependency direction between archlinux[arm]-keyring and pacman has been
reversed, so it needs to be installed explicitly. This makes the normal Arch
Linux keyring available on ARM, so we need to populate the ARM keyring even if
the regular one succeeds.

Dockerfile

@@ -8,7 +8,9 @@ RUN mkdir -p /archlinux/rootfs
 COPY pacstrap-docker /archlinux/
 
 RUN ./pacstrap-docker /archlinux/rootfs \
-	    bash sed gzip pacman && \
+      bash sed gzip pacman archlinux-keyring && \
+    # Install Arch Linux ARM keyring if available
+    (pacman -r /archlinux/rootfs -S --noconfirm archlinuxarm-keyring || true) && \
     # Remove current pacman database, likely outdated very soon
     rm rootfs/var/lib/pacman/sync/*
 
@@ -23,6 +25,7 @@ ENV LANG=en_US.UTF-8
 
 RUN locale-gen && \
     pacman-key --init && \
-    (pacman-key --populate archlinux || pacman-key --populate archlinuxarm)
+    pacman-key --populate archlinux && \
+    (pacman-key --populate archlinuxarm || true)
 
 CMD ["/usr/bin/bash"]