Fixing an error in helper balanced_reverse sorting

Found with rbx-head, Array#sort_by isn't a stable sort in rbx but
appears to be in most other Rubies. Thus the array

  [ [ '-', 1, 1 ],
    [ '-', 1, 2 ],
    [ '-', 2, 2 ] ]

would be sorted properly with the code

  #sort_by { |line| line[1] }

on most Rubies, but rbx might sort it as

  [ [ '-', 1, 2 ],
    [ '-', 1, 1 ],
    [ '-', 2, 2 ] ]

Changing the sort to

  #sort_by { |line| [ line[1], line[2] ] }

fixes this.

1 files changed, 1 insertions, 1 deletions

diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 60ee9e9..ff8fa71 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -142,7 +142,7 @@ module Diff::LCS::SpecHelper
       end
       new_result << line
     }
-    new_result.sort_by { |line| line[1] }
+    new_result.sort_by { |line| [ line[1], line[2] ] }
   end
 
   def map_to_no_change(change_result)