rails/rails — pull request #9776 by KensoDev (2013-03-18 17:08:56+00:00)
Title: Adding migrated_at timestamp to schema migrations

Knowing when a migration was executed is often really helpful when you
are trying to track down a problem in production or any other
environment for that matter.

I found myself in that position lots of times, so I thought it's worth
having this inside rails