Merge branch '17295_discussion_note' into 'master'

Fixes missing avatar on system notes

Closes #17295

![Screen_Shot_2016-06-27_at_12.50.50_PM](/uploads/b142226e608ccfe751a9b6059f57c9ec/Screen_Shot_2016-06-27_at_12.50.50_PM.jpg)

See merge request !4954
(cherry picked from commit 9e8fdead)

CHANGELOG

@@ -12,6 +12,7 @@ v 8.9.3
   - Use memorized tags array when searching tags by name. !4859
   - Fixed avatar alignment in new MR view. !4901
   - Removed fade when filtering results. !4932
+  - Fix missing avatar on system notes. !4954
 
 v 8.9.2
   - Fix visibility of snippets when searching.

app/assets/stylesheets/pages/notes.scss

@@ -41,6 +41,10 @@ ul.notes {
     .timeline-icon {
       .avatar {
         visibility: hidden;
+
+        .discussion-body & {
+          visibility: visible;
+        }
       }
     }
   }