FIX(CI) =~: unknown operand

.gitlab-ci.yml

@@ -49,10 +49,12 @@ docker-push:
     # else it is from a tag (enforced by gitlab-ci rules)
     # hint: tags are references independent of branches
     - |
-      if [ "$CI_COMMIT_BRANCH" == "$CI_DEFAULT_BRANCH" ]; then
-        docker login -u "$DOCKER_ID" -p "$DOCKER_HUB_AUTH" && docker build -t $AURA_IMAGE_NAME:unstable .
-      elif [ "$CI_MERGE_REQUEST_SOURCE_BRANCH_NAME" =~ "^feat" ]; then
-        docker login -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD" $CI_REGISTRY && docker build -t $AURA_IMAGE_NAME -t $AURA_IMAGE_NAME:$CI_MERGE_REQUEST_SOURCE_BRANCH_NAME
+      if [ "$CI_COMMIT_BRANCH" == "$CI_DEFAULT_BRANCH" ]
+      then
+      docker login -u "$DOCKER_ID" -p "$DOCKER_HUB_AUTH" && docker build -t $AURA_IMAGE_NAME:unstable .
+      elif expr "$CI_MERGE_REQUEST_SOURCE_BRANCH_NAME" : "^feat" > /dev/null
+      then
+      docker login -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD" $CI_REGISTRY && docker build -t $AURA_IMAGE_NAME -t $AURA_IMAGE_NAME:$CI_MERGE_REQUEST_SOURCE_BRANCH_NAME
       else
         docker login -u "$DOCKER_ID" -p "$DOCKER_HUB_AUTH" && docker build -t $AURA_IMAGE_NAME -t $AURA_IMAGE_NAME:$CI_COMMIT_TAG .
       fi