rails/rails — pull request #5261 by carlosantoniodasilva (2012-03-03 19:19:07+00:00)
Title: Remove IdentityMap

Identity Map was added in Rails 3.1 and due to some known issues with associations, it never graduated to be an "enabled-by-default" feature. Since we haven't seen any interest in solving such issues, I propose removing the feature from Rails codebase.

More info: https://github.com/rails/rails/commit/302c912