Root config option is inconsistent

[SamMousa]

This adapter has a configuration option called $root.
It is not documented but I think it is supposed to do something like $pathPrefix.

In practice however it doesn't really do this.

• When listing directory contents the path is prefix with $root.
• When doing anything else the path is not prefix with $root.

[SamMousa]

I just noticed it actually accidentally works in some cases; the root directory is set via chdir, so as long as that's not changed it seems to work ok.