Merge branch 'feature/jramsay/realtime-mr-widget' into 'master'

Real time merge request widget

See merge request gitlab-com/www-gitlab-com!34531

data/release_posts/unreleased/jramsay-realtime-mr-widget.yml

+features:
+  secondary:
+    - name: "Real-time merge request widget updates"
+      available_in: [core, starter, premium, ultimate]
+      documentation_link: "https://docs.gitlab.com/ee/user/project/merge_requests/"
+      reporter: jramsay
+      stage: create
+      issue_url: "https://gitlab.com/gitlab-org/gitlab/issues/31236"
+      description: |
+        Before clicking Merge, if you make a final tiny fix by pushing or
+        applying a suggestion, the merge button is disabled until you reload
+        the page. This slows down the final stages of review when applying the
+        final fixes. In GitLab 12.6, the merge request widget is now updated in
+        real-time so that you can merge immediately or when the pipeline
+        succeeds.