Error caused by modifying arguments

When passing the same array of column names into import for the list of column names, and for the list of on_duplicate_key_update option, the list is modified in places and causes sql queries with improper columns. Here is a rough patch

--- a/vendor/plugins/ar-extensions/lib/ar-extensions/import.rb
+++ b/vendor/plugins/ar-extensions/lib/ar-extensions/import.rb
@@ -175,7 +175,7 @@ class ActiveRecord::Base
         end
         # supports 2-element array and array
       elsif args.size == 2 and args.first.is_a?( Array ) and args.last.is_a?( Array )
-        column_names, array_of_attributes = args
+        column_names, array_of_attributes = args.first.dup, args.last.dup
       else
         raise ArgumentError.new( "Invalid arguments!" )
       end