Fixed typo in docker jobs

Change-Id: I1f40fb123557a44aec7a81ea786e081478eb1222
diff --git a/jenkins/client/job/docker/init.yml b/jenkins/client/job/docker/init.yml
index 6a5cb43..2056ee4 100644
--- a/jenkins/client/job/docker/init.yml
+++ b/jenkins/client/job/docker/init.yml
@@ -43,7 +43,7 @@
                 project:
                   "mk/docker-{{name}}":
                     branches:
-                      - {{branch}}
+                      - "{{branch}}"
                 event:
                   patchset:
                     - created: