run enterprise build only on master for now

.circleci/config.yml

@@ -8,6 +8,9 @@ aliases:
   - &filter-not-release
     tags:
       ignore: /^v[0-9]+(\.[0-9]+){2}(-.+|[^-.]*)$/
+  - &filter-only-master
+    branches:
+      only: master
 
 version: 2
 
@@ -242,7 +245,7 @@ workflows:
       - build-all:
           filters: *filter-not-release
       - build-enterprise:
-          filters: *filter-not-release
+          filters: *filter-only-master
       - codespell:
           filters: *filter-not-release
       - gometalinter:
@@ -277,9 +280,7 @@ workflows:
             - mysql-integration-test
             - postgres-integration-test
             - build-enterprise
-          filters:
-           branches:
-             only: master
+          filters: *filter-only-master
 
   release:
     jobs: