Relative path for drush status not working in drush 9

[jhedstrom]

Due to this drush issue (drush-ops/drush#2909), with drush 9, the relative path used for the --root arg, is not working properly, so we fail to detect the drupal major version.

One side effect of this is that modules suddenly start getting dumped into sites/all/modules since we fall back to D7 and earlier behavior for unknown Drupal versions.