Make diff discussion more reliable

app/models/merge_request.rb

@@ -861,11 +861,13 @@ class MergeRequest < ActiveRecord::Base
       paths: paths
     )
 
+    transaction do
       active_diff_notes.each do |note|
         service.execute(note)
         Gitlab::Timeless.timeless(note, &:save)
       end
     end
+  end
 
   def keep_around_commit
     project.repository.keep_around(self.merge_commit_sha)

changelogs/unreleased/fix_broken_diff_discussions.yml

+---
+title: Make MR-review-discussions more reliable
+merge_request:
+author: