Build tagged Docker images (#554)

.taskcluster.yml

@@ -138,13 +138,19 @@ tasks:
             privileged: true
           maxRunTime: 10800
           image: mozilla/taskboot:0.1.3
+          env:
+            REGISTRY: registry.hub.docker.com
+            VERSION:
+              $if: 'head_branch[:10] == "refs/tags/"'
+              then: {$eval: 'head_branch[10:]' }
+              else: "latest"
           command:
             - "/bin/sh"
             - "-lcxe"
             - "git clone ${repository} /code &&
                cd /code &&
                git checkout ${head_rev} &&
-               taskboot --cache /cache --target /code build-compose --registry=registry.hub.docker.com --write /images --build-arg CHECK_MODELS=0"
+               taskboot --cache /cache --target /code build-compose --write /images --build-arg CHECK_MODELS=0 --tag $VERSION --tag latest"
           artifacts:
             public/bugbug:
               expires: {$fromNow: '2 weeks'}