Various issues with become variables when using delegate_to in a loop

[ed-velez]

The easiest way to see the issue is just by using a simple play that calls the mitogen_get_stack module and uses the delegate_to option with a loop:

---
- hosts: all
  become: true
  gather_facts: false
  tasks:
    - name: Print mitogen debug
      mitogen_get_stack:
      run_once: true
      delegate_to: "{{ node }}"
      loop: "{{ ansible_play_hosts }}"
      loop_control:
        loop_var: node

When you run this on a simple inventory of 2 hosts with one host using sudo and the other using su - you will see that the sudo/su data is incorrect for one of the hosts. You will get garbage like the following for one of the hosts:

        {
            "enable_lru": true,
            "kwargs": {
                "connect_timeout": 10,
                "password": "<redacted>", <------- Incorrect password for escalation
                "python_path": [
                    "/usr/bin/python"
                ],
                "remote_name": null,
                "sudo_args": [],  <------- This can also be incorrect
                "sudo_path": "su", <------ Incorrect evaluation for become_exe
                "username": "root"
            },
            "method": "sudo"
        }

I've been able to come up with something that sort of roughly resolves my issue:

❯ git diff --patch
diff --git a/ansible_mitogen/transport_config.py b/ansible_mitogen/transport_config.py
index 5fc78185..780e0b81 100644
--- a/ansible_mitogen/transport_config.py
+++ b/ansible_mitogen/transport_config.py
@@ -410,7 +410,12 @@ class PlayContextSpec(Spec):
         self._play_context = play_context
         self._transport = transport
         self._inventory_name = inventory_name
-        self._task_vars = self._connection._get_task_vars()
+        task_vars = self._connection._get_task_vars()
+        if 'ansible_delegated_vars' in task_vars and self._connection.delegate_to_hostname:
+            self._task_vars = task_vars['ansible_delegated_vars'][self._connection.delegate_to_hostname]
+        else:
+            self._task_vars = task_vars
+
         # used to run interpreter discovery
         self._action = connection._action

@@ -436,9 +441,7 @@ class PlayContextSpec(Spec):
         return self._play_context.become_user

     def become_pass(self):
-        become_method = self.become_method()
-        become_plugin = ansible_mitogen.loaders.become_loader.get(become_method)
-        become_pass = become_plugin.get_option('become_pass', hostvars=self._task_vars)
+        become_pass = C.config.get_config_value("become_pass", plugin_type="become", plugin_name=self.become_method(), variables=self._task_vars)
         return optional_secret(become_pass)

     def password(self):
@@ -486,28 +489,13 @@ class PlayContextSpec(Spec):
         ]

     def become_exe(self):
-        # In Ansible 2.8, PlayContext.become_exe always has a default value due
-        # to the new options mechanism. Previously it was only set if a value
-        # ("somewhere") had been specified for the task.
-        # For consistency in the tests, here we make older Ansibles behave like
-        # newer Ansibles.
-        exe = self._play_context.become_exe
-        if exe is None and self._play_context.become_method == 'sudo':
-            exe = 'sudo'
-        return exe
+        return C.config.get_config_value("become_exe", plugin_type="become", plugin_name=self.become_method(), variables=self._task_vars)

     def sudo_args(self):
         return [
             mitogen.core.to_text(term)
             for term in ansible.utils.shlex.shlex_split(
-                first_true((
-                    self._play_context.become_flags,
-                    # Ansible <=2.7.
-                    getattr(self._play_context, 'sudo_flags', ''),
-                    # Ansible <=2.3.
-                    getattr(C, 'DEFAULT_BECOME_FLAGS', ''),
-                    getattr(C, 'DEFAULT_SUDO_FLAGS', '')
-                ), default='')
+                C.config.get_config_value("become_flags", plugin_type="become", plugin_name="sudo", variables=self._task_vars) or ''
             )
         ]

I encountered the bug with mitogen 0.3.4 and I am currently using Ansible 2.11.12. I am happy to submit the above in a PR but I noticed you had a couple of PR's working on similar areas in the transport_config. Let me know if I can help get this addressed.