This brings up an interesting point. Let:

* `--path` be the runtime parameter you pass to `wp`
* `path:` the config you set in a `wp-cli.yml` file.

When either of them is absolute, there's no problem.

When they're relative, it gets tricky: `--path` can be relative to the user's current working directory, while `path:` is relative to the file it's in.

The problem is that, at this point in the execution, `--path` would have overwritten `path:`, so you can't tell where the value came from.