rails/rails — pull request #14333 by quainjn (2014-03-09 22:08:53+00:00)
Title: Fix serialized attributes always being saved

Fixes #8328. Models with serialized attributes will only be saved if the record has changed.

Uses #hash to compare original serialize attribute value to current value. Similar to #13428

Chose to use #hash for comparison for performance reasons. The downside of using #hash rather than #deep_dup is that serialized_attribute_was will not be stored, and will return nil.