Issue with using ERL_EPMD_PORT environment variable

[lukebakken]

Reported here

Steps to reproduce:

• Set ERL_EPMD_PORT to something other than 4369 in /etc/rabbitmq/rabbitmq-env.conf
• Start RabbitMQ
• RabbitMQ will start epmd on port 4369 (whoops)
• Running epmd -names shows that RabbitMQ has registered using that epmd process.
• rabbitmqctl status will fail since it thinks the other epmd port is being used