The following issue affects the currently latest maintenance update for Leap
42.1 for rabbitmq-server, 3.5.1-4.1. It works fine with 3.5.1-2.7.

When starting epmd via service, rabbitmq-server fails to start. It works if we
don't start epmd from the service, but instead let rabbitmq start it. A few
command outputs below:

## working scenario

odb:~ # ps aux | grep epmd | grep -v grep
odb:~ # rcrabbitmq-server start
odb:~ # rcrabbitmq-server status
rabbitmq-server.service - RabbitMQ broker
   Loaded: loaded (/usr/lib/systemd/system/rabbitmq-server.service; enabled)
   Active: active (running) since Wed 2016-10-05 13:02:44 UTC; 2s ago
  Process: 5615 ExecStop=/usr/sbin/rabbitmqctl stop (code=exited,
status=0/SUCCESS)
 Main PID: 5750 (epmd)
   Status: "Exited."
   CGroup: /system.slice/rabbitmq-server.service
           ������5731 /bin/sh /usr/sbin/rabbitmq-server
           ������5735 /usr/lib64/erlang/erts-7.0.3/bin/beam.smp -W w -K true -A30
-P 1048576 -- -root /usr/lib64/erlang -progname erl -- -home /var/lib/rabbitmq
-- -pa /usr/lib64/rabbitmq/lib/rabbitmq_server-3.5.1/sbin/../ebin -noshell
-noinput -s rabbit boot -sname rabbit@localhost -boot start_sasl -config
/etc/rabbitmq/rabbitmq -kernel inet_default_connect_options [{nodelay,true}]
-rabbit tcp_listeners [{"auto",5672}] -sasl errlog_type error -sasl
sasl_error_logger false -rabbit error_logger
{file,"/var/log/rabbitmq/rabbit@localhost.log"} -rabbit sasl_error_logger
{file,"/var/log/rabbitmq/rabbit@localhost-sasl.log"} -rabbit
enabled_plugins_file "/etc/rabbitmq/enabled_plugins" -rabbit plugins_dir
"/usr/lib64/rabbitmq/lib/rabbitmq_server-3.5.1/sbin/../plugins" -rabbit
plugins_expand_dir "/var/lib/rabbitmq/mnesia/rabbit@localhost-plugins-expand"
-os_mon start_cpu_sup false -os_mon start_disksup false -os_mon start_memsup
false -mnesia dir "/var/lib/rabbitmq/mnesia/rabbit@localhost" -kernel
inet_dist_listen_min 25672 -kernel inet_dist_listen_max 25672
           ������5750 /usr/lib64/erlang/erts-7.0.3/bin/epmd -daemon

Oct 05 13:02:44 odb systemd[1]: Starting RabbitMQ broker...
Oct 05 13:02:44 odb systemd[1]: Started RabbitMQ broker.
odb:~ # ps aux | grep epmd | grep -v grep
rabbitmq  5750  0.0  0.0  25228   208 ?        S    13:02   0:00
/usr/lib64/erlang/erts-7.0.3/bin/epmd -daemon

## non-working scenario
odb:~ # ps aux | grep epmd | grep -v grep
odb:~ # rcepmd start
odb:~ # rcepmd status
epmd.service - Erlang Port Mapper Daemon
   Loaded: loaded (/usr/lib/systemd/system/epmd.service; enabled)
   Active: active (running) since Wed 2016-10-05 13:05:14 UTC; 1s ago
 Main PID: 5992 (epmd)
   CGroup: /system.slice/epmd.service
           ������5992 /usr/bin/epmd -systemd

Oct 05 13:05:14 odb systemd[1]: Starting Erlang Port Mapper Daemon...
Oct 05 13:05:14 odb systemd[1]: Started Erlang Port Mapper Daemon.
odb:~ # ps aux | grep epmd | grep -v grep
epmd      5992  0.0  0.0  25228  1480 ?        Ss   13:05   0:00 /usr/bin/epmd
-systemd
odb:~ # rcrabbitmq-server start
Job for rabbitmq-server.service failed. See "systemctl status
rabbitmq-server.service" and "journalctl -xn" for details.

journactl reports:
Oct 05 13:07:18 odb systemd[1]: Starting RabbitMQ broker...
Oct 05 13:07:18 odb systemd[1]: Cannot find unit for notify message of PID
6294.
Oct 05 13:08:48 odb systemd[1]: rabbitmq-server.service start operation timed
out. Terminating.
Oct 05 13:08:48 odb systemd[1]: Failed to start RabbitMQ broker.
Oct 05 13:08:48 odb systemd[1]: Unit rabbitmq-server.service entered failed
state.