ShareThis module uses the wrong URL to share

We use the ShareThis widget as a block. Country code is in the base path. So a typical blog post has the URL: http://www.example.com/in/blog/drupal-works

When we use a ShareThis service, it shares the URL: http://www.example.com/in//in/blog/drupal-works

This happens because the span attribute st_url has the wrong URL. I traced it down to sharethis/src/Plugin/Block/SharethisWidgetBlock.php code that builds the absolute URL:

        $current_path = Url::fromRoute('')->toString();
        $path = ($this->configuration['sharethis_path'] == 'global') ? '' : $current_path;

        global $base_url;
        $path_obj = Url::fromUri($base_url . '/' . $path,
          array(
            'absolute' => TRUE,
          )
        );
        $mpath = $path_obj->toString();

If I replace $base_url to get:

        $path_obj = Url::fromUri('internal:/' . $path,
          array(
            'absolute' => TRUE,
          )
        );

it works fine for our site. However, I am not sure if using internal is the correct code.

Apologies if this issue turns out to be a duplicate. I searched through the issue queue and found a couple of issues that affected SharethisManager.php, but not SharethisWidgetBlock.php.