another try for docker caching

.gitlab-ci.yml

@@ -49,10 +49,10 @@ build:
         echo "Building Heroku-based application using gliderlabs/herokuish docker image..."
         cp /build/Dockerfile Dockerfile
       fi
-    - docker pull $CI_APPLICATION_REPOSITORY:$CI_APPLICATION_TAG || true
+    - docker pull $CI_APPLICATION_REPOSITORY:latest || true
     - |
       docker build \
-        --cache-from $CI_APPLICATION_REPOSITORY:$CI_APPLICATION_TAG \
+        --cache-from $CI_APPLICATION_REPOSITORY:latest \
         --build-arg BUILDPACK_URL="$BUILDPACK_URL" \
         --build-arg HTTP_PROXY="$HTTP_PROXY" \
         --build-arg http_proxy="$http_proxy" \
@@ -64,6 +64,7 @@ build:
         --build-arg no_proxy="$no_proxy" \
         $AUTO_DEVOPS_BUILD_IMAGE_EXTRA_ARGS \
         --tag "$CI_APPLICATION_REPOSITORY:$CI_APPLICATION_TAG" .
+    - docker push "$CI_APPLICATION_REPOSITORY:latest"
     - docker push "$CI_APPLICATION_REPOSITORY:$CI_APPLICATION_TAG"
   only:
     - branches