[FIX] forum: restore superuser bypass in per-post karma check

During conversion to new API[1] the superuser bypass
was dropped in the computation of karma-based
permissions on forum posts.
The check still needs to be bypassed to avoid
blocking sudo() mode when the admin account
has a low karma.
sudo() mode is used for various actions done
by the system on behalf of the forum users,
and should not fail because the admin has less
karma than the user herself.

[1] See rev. 893d7fa864

addons/website_forum/models/forum.py

@@ -294,6 +294,7 @@ class Post(models.Model):
     @api.multi
     def _get_post_karma_rights(self):
         user = self.env.user
+        is_admin = user.id == SUPERUSER_ID
         # sudoed recordset instead of individual posts so values can be
         # prefetched in bulk
         for post, post_sudo in itertools.izip(self, self.sudo()):
@@ -306,17 +307,17 @@ class Post(models.Model):
             post.karma_comment = post.forum_id.karma_comment_own if is_creator else post.forum_id.karma_comment_all
             post.karma_comment_convert = post.forum_id.karma_comment_convert_own if is_creator else post.forum_id.karma_comment_convert_all
 
-            post.can_ask = user.karma >= post.forum_id.karma_ask
-            post.can_answer = user.karma >= post.forum_id.karma_answer
-            post.can_accept = user.karma >= post.karma_accept
-            post.can_edit = user.karma >= post.karma_edit
-            post.can_close = user.karma >= post.karma_close
-            post.can_unlink = user.karma >= post.karma_unlink
-            post.can_upvote = user.karma >= post.forum_id.karma_upvote
-            post.can_downvote = user.karma >= post.forum_id.karma_downvote
-            post.can_comment = user.karma >= post.karma_comment
-            post.can_comment_convert = user.karma >= post.karma_comment_convert
-            post.can_view = user.karma >= post.karma_close or post_sudo.create_uid.karma > 0
+            post.can_ask = is_admin or user.karma >= post.forum_id.karma_ask
+            post.can_answer = is_admin or user.karma >= post.forum_id.karma_answer
+            post.can_accept = is_admin or user.karma >= post.karma_accept
+            post.can_edit = is_admin or user.karma >= post.karma_edit
+            post.can_close = is_admin or user.karma >= post.karma_close
+            post.can_unlink = is_admin or user.karma >= post.karma_unlink
+            post.can_upvote = is_admin or user.karma >= post.forum_id.karma_upvote
+            post.can_downvote = is_admin or user.karma >= post.forum_id.karma_downvote
+            post.can_comment = is_admin or user.karma >= post.karma_comment
+            post.can_comment_convert = is_admin or user.karma >= post.karma_comment_convert
+            post.can_view = is_admin or user.karma >= post.karma_close or post_sudo.create_uid.karma > 0
 
     @api.one
     @api.constrains('post_type', 'forum_id')