fix the cloud build

Signed-off-by: James Strong <strong.james.e@gmail.com>

images/nginx/cloudbuild.yaml

@@ -8,7 +8,7 @@ steps:
     entrypoint: bash
     env:
       - DOCKER_CLI_EXPERIMENTAL=enabled
-      - TAG=v$(date "+%Y%m%d")-$SHORT_SHA
+      - COMMIT=$SHORT_SHA
       - BASE_REF=$_PULL_BASE_REF
       - REGISTRY=gcr.io/k8s-staging-ingress-nginx
       # default cloudbuild has HOME=/builder/home and docker buildx is in /root/.docker/cli-plugins/docker-buildx
@@ -18,7 +18,7 @@ steps:
     - -c
     - |
       gcloud auth configure-docker \
-      && make push
+      && TAG=v$(date "+%Y%m%d")-${COMMIT} make push
 substitutions:
   _GIT_TAG: "12345"
   _PULL_BASE_REF: "master"