Try installing latest version of erlang and rabbitmq-server package.

.travis.yml

@@ -67,19 +67,20 @@ addons:
       - mongodb-upstart
       - sourceline: 'deb [arch=amd64] http://repo.mongodb.org/apt/ubuntu precise/mongodb-org/3.4 multiverse'
         key_url: 'https://www.mongodb.org/static/pgp/server-3.4.asc'
+      # NOTE: Precise repo doesn't contain Erlang 20.x, latest version is 19.x so we need to use RabbitMQ 3.7.6
+      - sourceline: 'deb [arch=amd64] http://packages.erlang-solutions.com/ubuntu precise contrib'
+        key_url: 'https://packages.erlang-solutions.com/ubuntu/erlang_solutions.asc'
+      - sourceline: 'deb [arch=amd64] https://dl.bintray.com/rabbitmq/debian precise rabbitmq-server-v3.7.x'
+        key_url: '/~https://github.com/rabbitmq/signing-keys/releases/download/2.0/rabbitmq-release-signing-key.asc'
       - sourceline: 'ppa:git-core/ppa'
     packages:
       - mongodb-org-server
       - mongodb-org-shell
-      # NOTE: Uncomment below for Xenial
-      # -rabbitmq-server
+      - erlang
+      - rabbitmq-server=3.7.6-1
       - git
       - libffi-dev
 
-# NOTE: Remove / comment services section below for Xenial
-services:
-  - rabbitmq
-
 cache:
   pip: true
   directories: