Drush relative root still not working

[eporama]

Describe the bug
On a vanilla install of Drupal-project, drush called from the project directory with a --root parameter is returning The "drush/sites" directory does not exist.

To Reproduce

$ composer create-project drupal-composer/drupal-project:8.x-dev test-drush --no-interaction
Installing drupal-composer/drupal-project (8.x-dev ec0f41171516c18357ca4cda9068ee4cdeabaa19)
  - Installing drupal-composer/drupal-project (8.x-dev ec0f411): Cloning ec0f411715 from cache
Created project in test-drush
…<snip>…

$ cd test-drush

$  vendor/bin/drush status
 Drupal version : 8.7.1
 Site URI       : http://default
 PHP binary     : /usr/local/Cellar/php@7.1/7.1.25/bin/php
 PHP config     : /usr/local/etc/php/7.1/php.ini
 PHP OS         : Darwin
 Drush script   : /private/tmp/test-drush/vendor/drush/drush/drush
 Drush version  : 9.6.2
 Drush temp     : /tmp
 Drush configs  : /private/tmp/test-drush/vendor/drush/drush/drush.yml
                  /private/tmp/test-drush/drush/drush.yml
 Drupal root    : /private/tmp/test-drush/web
 Site path      : sites/default

$  vendor/bin/drush --root=web status

In Finder.php line 547:

  The "drush/sites" directory does not exist.

$ cd web

$ ../vendor/bin/drush status --field=root
/private/tmp/test-drush/web

Expected behavior

I would expect that drush status works with --root

Actual behavior
Drush couldn't determine it's location and requires a drush/sites directory, however even if one exists, that doesn't solve the problem.

total 8
-rw-r--r--  1 myusername  wheel  342 May 10 14:19 self.site.yml

Workaround
The status works without the root if drush can automatically determine a root or if you are within the root.

System Configuration

Q	A
Drush version?	9.6.2
Drupal version?	8.7.1
PHP version	7.1
OS?	MacOS Mojave (10.14.4)

Additional information
Looked at #2909 and #4019 but they seem to be similar, but "fixed"

[eporama]

It does appear to be "relative" that is the issue as a full path does work:

$ vendor/bin/drush --root=/private/tmp/test-drush status --field=root
/private/tmp/test-drush/web

[eporama]

It appears that the issue is directly related to webflo/drupal-finder#40. Manually applying the patch from that issue solves this problem. Hopefully we can get a release of that soon.