An empty line after guard, feedback:

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5142#note_13904931

app/models/merge_request.rb

@@ -676,6 +676,7 @@ class MergeRequest < ActiveRecord::Base
 
   def pipeline
     return unless diff_head_sha && source_project
+
     @pipeline ||= source_project.pipeline_for(source_branch, diff_head_sha)
   end