Use correct user for 'Discussion resolved by...'

app/models/discussion.rb

@@ -21,7 +21,8 @@ class Discussion
   delegate  :resolved_at,
             :resolved_by,
-            to: :last_note
+            to: :last_resolved_note,
+            allow_nil: true
   delegate :blob, :highlighted_diff_lines, to: :diff_file, allow_nil: true
@@ -39,6 +40,12 @@ class Discussion
     @notes = notes
   end
+  def last_resolved_note
+    return unless resolved?
+
+    @last_resolved_note ||= resolved_notes.sort_by(&:resolved_at).last
+  end
+
   def last_updated_at
     last_note.created_at
   end
@@ -67,6 +74,10 @@ class Discussion
     resolvable? && notes.none?(&:to_be_resolved?)
   end
+  def resolved_notes
+    notes.select(&:resolved?)
+  end
+
   def to_be_resolved?
     notes.any?(&:to_be_resolved?)
   end

app/models/merge_request.rb

@@ -395,15 +395,18 @@ class MergeRequest < ActiveRecord::Base
   end
   def discussions
-    self.mr_and_commit_notes.
+    @discussions ||= self.mr_and_commit_notes.
       inc_author_project_award_emoji.
       fresh.
       discussions
   end
+  def discussions_resolvable?
+    discussions.any?(&:resolvable?)
+  end
+
   def discussions_resolved?
-    all_discussions = discussions
-    all_discussions.any?(&:resolvable?) && all_discussions.none?(&:to_be_resolved?)
+    discussions_resolvable? && discussions.none?(&:to_be_resolved?)
   end
   def hook_attrs