This reverts commit 9c01d875f3.
This is very confusing and messy.. but it's documented.
`ansible_become_*` variables actually take priority and override all `become_*`
variables set at the task level.
As such, using `ansible_become=true ansible_become_user=root` in
`inventory/hosts` causes issues because tasks that specify
`become: OTHER_USER` will be forced to run as `root` due to
`ansible_become_user`.
Putting a lot of comments inbetween `[matrix-servers]` and the example
host line may make someone decide to clean up the comment
and accidentally skip-over the `[matrix-servers]` part.
