rails/rails — pull request #5643 by rafaelfranca (2012-03-28 22:04:05+00:00)
Title: Remove code duplication in InclusionValidator and ExclusionValidator.

I got the implementation in #1352 by @jamescook and changed to use composition instead of inheritance.

I tried to cherry-pick the original commit to give credits to the original author but he deleted their fork, so I added it as co-author in the commit message.