Update IPv6.

builder/build-docker.sh

@@ -90,6 +90,7 @@ else
 	time ${DOCKER} run --name "${CONTAINER_NAME}" --privileged \
 		--volume "${CONFIG_FILE}":/config:ro \
 		-e "GIT_HASH=${GIT_HASH}" \
+		--ipv6 \
 		pi-gen \
 		bash -e -o pipefail -c "dpkg-reconfigure qemu-user-static &&
 	cd /pi-gen; ./build.sh ${BUILD_OPTS} &&