Hide harmless warning about Portage sandboxes

See also: stage0@9f790786

.gitlab-ci.yml

@@ -18,6 +18,7 @@ default:
                    --build-arg STAGE0_TAG="$CPU"
                    --build-arg FACTER_emerge_default_opts="$CI_HOST_EMERGE_DEFAULT_OPTS"
                    --build-arg FACTER_makeopts="$CI_HOST_MAKEOPTS"
+                   --build-arg FEATURES="-ipc-sandbox -pid-sandbox -network-sandbox"
                    --build-arg PROFILE="${CPU}/${ROLE}"
                    -v "/usr/bin/qemu-${QEMU_ARCH}:/usr/bin/qemu-${QEMU_ARCH}:ro"
                    -v "${PUPPET_CERTIFICATE}:/etc/puppetlabs/puppet/ssl/certs/ci.pem"

Containerfile

@@ -3,6 +3,7 @@ FROM nest/stage0:${STAGE0_TAG}
 
 ARG FACTER_emerge_default_opts
 ARG FACTER_makeopts
+ARG FEATURES
 ARG PROFILE
 
 RUN eix-sync -q