Until Ansible 2.9 it looks like ansible_become_password had higher priority.
From Ansible 2.10 ansible_become_pass has higher priority [1]. Mitogen was not
respecting this.
I may need to rework this further, instatiating the become plugin may have
slowed down execution.
[1] Based on testing with
```
[ubuntus]
become-pass-pass ansible_become_pass=1234
become-pass-password ansible_become_password=1234
become-pass-both ansible_become_password=wrong ansible_become_pass=1234
[ubuntus:vars]
ansible_host=ubuntu2004.local
ansible_user=ubuntu
```
```
- hosts: ubuntus
gather_facts: false
become: true
tasks:
- ping:
```