vm-img: ignore gpg errors with archive.debian.org

Is there an option to only ignore KEYEXPIRED ?

component/vm-img/debian.cfg

@@ -25,6 +25,8 @@ recipe = slapos.recipe.build:vm.install-debian
 environment = vm-install-environment
 dists = debian-stable
 size = 1Gi
+preseed.partman/early_command =
+  set -e /usr/lib/apt-setup/generators/99 AllowUnauthenticated; if [ "`debconf-get mirror/http/hostname`" = archive.debian.org ]; then echo "echo 'APT::Get::$2 \"true\";' >/target/etc/apt/apt.conf.d/01$2" >$1$2; chmod +x $1$2; fi
 late-command =
 # rdnssd causes too much trouble with recent QEMU, because the latter acts as
 # a DNS proxy on both IPv4 and IPv6 without translating queries to what the