pub fn to_wait(&self) -> Ticket {
		self.send_controls([Control::NextEnding], Priority::High)
	}
Get a future which resolves when the command ends.

If the command is not running, the future resolves immediately.

The underlying control message is sent with higher priority than normal, so it targets the
actively running command, not the one that will be running after the rest of the controls
get done; note that may still be racy if the command ends between the time the message is
sent and the time it's processed.
crates/supervisor/src/job/job.rs