trptcolin/consistency_fail — pull request #7 by leomayleomay (2013-07-18 05:55:23+00:00)
Title: 1, add polymorphic check for the has_one association

Hi,

I read (the post)[http://robots.thoughtbot.com/post/55689359336/the-perils-of-uniqueness-validations] this morning, and I think we should have compound unique index for polymorphic has_one association, here's my pull request, please help to review and merge, thanks a lot