rails/rails — pull request #3823 by avakhov (2011-12-01 05:17:30+00:00)
Title: Fix argument error message for length validation

[activemodel/lib/active_model/validations/length.rb](https://github.com/rails/rails/blob/a604983f8b8b873558fe7838d0bfcf0e0594daa6/activemodel/lib/active_model/validations/length.rb#L13) supports both :in and :within