template_preprocess_comment() is inconsistent with uri() and permalink()

Coming from #1970360-99: Entities should define URI templates and standard links

Reference: https://api.drupal.org/api/drupal/core!modules!comment!comment.module/function/template_preprocess_comment/8

Problem description

1. The following two code snippets are inconsistent with each other:
   
   <?php
  $permalink_uri = $comment->permalink();
  $uri['options'] += array('attributes'=> array(
    'class'=> 'permalink',
    'rel'=> 'bookmark',
  ));
?>
   
   
   <?php
    $permalink_uri_parent = $comment_parent->permalink();
    $permalink_uri_parent['options'] += array('attributes'=> array(
      'class'=> array('permalink'),
      'rel'=> 'bookmark',
    ));
?>
   
   It seems as though the latter is correct and the former is simply a typo. Not sure.
2. The following two code snippets are also inconsistent with each other:
   
   <?php
  $variables['title'] = l($comment->subject->value, $uri['path'], $uri['options']);
?>
   
   
   <?php
    $variables['parent_title'] = l($comment_parent->subject->value, $permalink_uri_parent['path'], $permalink_uri_parent['options']);
?>
   
   In this case it seems as though the former is correct.