Comment 17 for bug 1536810

Hm, i don't think update-initramfs does the right thing:

linux-image-*)
        if [ -z "$INITRAMFS_TOOLS_KERNEL_HOOK" ]; then
                # kernel maintainer script called us directly; ignore
                # it and let the hook script handle it instead
                echo "update-initramfs: deferring update (hook will be called later)"
                exit 0
        fi
        ;;

it seems like a special variable needs to be set, to actually make initramfs create things.