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:
2a3091c9c2c73e469e19
Change-Id: Ia8f053e499db7aa7c78c60213d3154d967b92a98
(cherry picked from commit b7247285e5)