title: Change remote user in custom module
body: <p>I'm developing a custom network module for Ansible 2.5.2 for MikroTik RouterOS. </p>
  
  <p>I want to change the remote username under the hood, e.g. if in my inventory I have <code>ansible_user: ansible</code>, I would like to change it to <code>ansible_user: ansible+cet</code>.</p>
  
  <p>I have seen modules that do this in action plugins, like here: <a href="https://github.com/CFSworks/ansible-routeros/blob/master/action_plugins/routeros.py#L56" rel="nofollow noreferrer">CFSworks/ansible-routeros</a>. 
  However, it seems that in Ansible 2.5 with <code>network_cli</code> connection type this is no longer the case. When I add the following sample action plugin to <code>plugins/action</code> directory nothing happens – I don't see <code>routeros action plugin is called</code> in debug console: </p>
  
  <pre><code>class ActionModule(_ActionModule):
  
      def run(self, tmp=None, task_vars=None):
          display.debug('routeros action plugin is called')
          result = super(ActionModule, self).run(task_vars=task_vars)
          return result
  </code></pre>
  
  <p>This is my playbook:</p>
  
  <pre><code>- hosts: routeros
      gather_facts: no
      connection: network_cli
      tasks:
        - ...
  </code></pre>
  
  <p>And this is my inventory:</p>
  
  <pre><code>routeros:
    hosts:
      example:
        ansible_host: 192.168.88.1
        ansible_user: ansible
        # ansible_user: ansible+cet &lt;-- i want to add '+cet' on the fly
        ansible_ssh_pass: ansible
        ansible_network_os: routeros
  </code></pre>
  
  <p>What is the proper way to replace the connection user in Ansible 2.5 with <code>network_cli</code> connection type?</p>