Merge branch 'rs-fix-already-defined-constant' into 'master'

Fix NUMBER_OF_TRUNCATED_DIFF_LINES re-definition error

See merge request !10664

app/models/concerns/discussion_on_diff.rb

@@ -2,9 +2,9 @@
 module DiscussionOnDiff
   extend ActiveSupport::Concern
 
-  included do
   NUMBER_OF_TRUNCATED_DIFF_LINES = 16
 
+  included do
     delegate  :line_code,
               :original_line_code,
               :diff_file,