rails/rails — pull request #9975 by mmangino (2013-03-28 15:20:59+00:00)
Title: Unserializing YAML attributes can silently fail in development mode

If you use a serialized attribute on an ActiveRecord model and the object to be unserialized has not yet been loaded, AR will silently return the YAML string. This can be confusing to new users and apparently to me, even though I've been bitten by this three or four times in the past.