Pin erlang packages to version 19.3

Erlang 20 has been released and is not compatible with the current
release of RabbitMQ.[0] Pin erlang packages to the latest version
version supported by RabbitMQ 3.6.x, 19.3.

For package pinning to work correctly on Ubuntu, the priority of pinning
to a specific version needs to be higher than the priority of all
packages coming from the ESL repo.

For RedHat distros, the yum-versionlock plugin will need to be installed
and used to properly pin a package to a specific version.
[0] https://groups.google.com/forum/#!topic/rabbitmq-users/_imbAavBYjY

Combined back port of the following commits:
2a3091c9c2
c73e469e19

Change-Id: Ia8f053e499db7aa7c78c60213d3154d967b92a98

meta/main.yml

@@ -39,5 +39,8 @@ dependencies:
     apt_pinned_packages:
       - package: "*"
         release: "Erlang Solutions Ltd."
+      - package: "erlang*"
+        version: "1:19.3*"
+        priority: 1000
     when:
       - ansible_pkg_mgr == 'apt'

tasks/install_yum.yml

@@ -73,6 +73,32 @@
   tags:
     - rabbitmq-repos
 
+- name: Enable and set erlang repo priority
+  command: |
+    yum-config-manager
+      --enable {{ item.name }}
+      --setopt="{{ item.name }}.priority={{ item.priority }}"
+  changed_when: false
+  with_items:
+    - name: "{{ rabbitmq_erlang_repo.name }}"
+      priority: 40
+  tags:
+    - rabbitmq-repos
+
+- name: Install yum versionlock plugin
+  yum:
+    name: "yum-plugin-versionlock"
+    state: "{{ rabbitmq_package_state }}"
+  tags:
+    - rabbitmq-yum-packages
+
+- name: Lock version of erlang packages
+  command: yum versionlock add erlang*19.3*
+  register: yum_versionlock_erlang
+  changed_when: "yum_versionlock_erlang.stdout.find('versionlock added: 0') == -1"
+  tags:
+    - rabbitmq-yum-packages
+
 - name: Install RabbitMQ package dependencies
   yum:
     pkg: "{{ item }}"