provision-delete on a platform doesn't always work without a verify

So this is odd, because that error is provided by a FALSE result of provision_drupal_find_sites(), which literally looks for a 'settings.php' in any subdir of the platform.

function provision_drupal_find_sites() {
  if ($dir = opendir("./sites")) {
    while (FALSE !== ($subdir = readdir($dir))) {
      // skip internal directory pointers
      if ($subdir != '.' && $subdir != '..') {
        $file = "./sites/$subdir/settings.php";
        if (file_exists("$file") && ($subdir != 'default') && !is_link("./sites/$subdir")) {
          $sites[$subdir] = $file;
        }
      }
    }
    closedir($dir);
  } else {
    drush_log(dt("Cannot find sites directory"), 'error');
    $sites = FALSE;
  }
  return $sites;
}

evaluated in provision_drupal_provision_delete():

elseif (d()->type === 'platform') {
    if (provision_drupal_find_sites()) {
      drush_set_error(dt('Existing sites were found on this platform. These sites will need to be deleted before this platform can be deleted.'));
    }
    else {
      _provision_recursive_delete(d()->root);
      d()->service('http')->sync(d()->root);
    }
  }

So, were there any other factors at play here, i.e:

1) There was no settings.php in the 'all' or 'default' dir in that platform's 'sites' dir by any chance?
2) Anything else 'different' from usual, such as the platform being a remote server or something? Wondering if it's related to all the syncing stuff that goes on with multiserver, since the 'Delete' task on platforms predates that.

And I'm guessing it's a lovely random thing that sometimes works?