Out of the box cluster pillar example results in errors when applied

    Function: file.managed
        Name: /etc/rabbitmq/rabbitmq.config
      Result: False
     Comment: Unable to manage file: Jinja error: argument of type 'StrictUndefined' is not iterable
              Traceback (most recent call last):
                File "/usr/lib/python2.7/site-packages/salt/utils/templates.py", line 380, in render_jinja_tmpl
                  output = template.render(**decoded_context)
                File "/usr/lib/python2.7/site-packages/jinja2/environment.py", line 969, in render
                  return self.environment.handle_exception(exc_info, True)
                File "/usr/lib/python2.7/site-packages/jinja2/environment.py", line 742, in handle_exception
                  reraise(exc_type, exc_value, tb)
                File "<template>", line 39, in top-level template code
              TypeError: argument of type 'StrictUndefined' is not iterable

              ; line 39

              ---
              [...]

                            {% endif %}

                           ]
                  }
                  {%- if 'rabbitmq_management' in server.plugins %},    <======================
                  {rabbitmq_management,
                            [{listener, [{port, {{ server.management.bind.port }} },
                                         {ip, "{{ server.management.bind.address }}" }
                                         {%- if server.management.get('ssl', {}).get('enabled', False) %},
                                         {ssl,true},
              [...]
              ---
     Started: 15:49:13.745648
    Duration: 113.444 ms
     Changes:
salt-formulas / salt-formula-rabbitmq

Out of the box cluster pillar example results in errors when applied #51
