Build changemessage plugin for Gerrit v3.{1,2}

Change-Id: Icc7b6ebf34556ba399d48149d49808f4c8031f60
diff --git a/jenkins/gerrit-bazel-plugin-changemessage.yaml b/jenkins/gerrit-bazel-plugin-changemessage.yaml
index 0ff1f3b..600dc8b 100644
--- a/jenkins/gerrit-bazel-plugin-changemessage.yaml
+++ b/jenkins/gerrit-bazel-plugin-changemessage.yaml
@@ -1,6 +1,13 @@
 - project:
     name: changemessage
     jobs:
+      - 'plugin-{name}-bazel-{branch}-{gerrit-branch}':
+          branch:
+            - master
+          gerrit-branch:
+            - master
+            - stable-3.2
+            - stable-3.1
       - 'plugin-{name}-bazel-{branch}':
           branch:
             - master