[minor] fix container build in travisci

.travis.yml

@@ -31,15 +31,13 @@ script:
     - sed -i 's,//_,_,' conf/available_modules.go
     - make
     - docker build -t mozilla/mig .
-    # If a TRAVIS_TAG is set, this build follows a git tag --push and should trigger
-    # a release of a tagged container to dockerhub. Otherwise, we tag as latest.
     - |
-        docker login -e $DOCKER_EMAIL -u $DOCKER_USER -p $DOCKER_PASS
         if [ ! -z "$TRAVIS_TAG" ]; then
-            docker tag app:build mozilla/mig:${TRAVIS_TAG}
-            docker push mozilla/mig:${TRAVIS_TAG}
-        else
-            docker tag app:build mozilla/mig:latest
-            docker push mozilla/mig:latest
+            # If a TRAVIS_TAG is set, this build follows a git tag --push and should trigger
+            # a release of a tagged container to dockerhub. Otherwise, we tag as latest.
+            docker login -e $DOCKER_EMAIL -u $DOCKER_USER -p $DOCKER_PASS
+            docker tag mozilla/mig mozilla/mig:${TRAVIS_TAG}
+            docker tag mozilla/mig mozilla/mig:latest
+            docker push mozilla/mig
         fi
         docker logout