abrandoned/activerecord-committed_observer — pull request #1 by devin-c (2013-02-13 00:44:52+00:00)
Title: warn only when the method is already defined

Including ActiveRecord::CommittedObserver was always displaying the
warning message because Module.included? is called after the modules
features have been appended to the class. This update checks for the
presence of after_commit before the features are appended to the
class--squelching the overzealous warnings. Defining after_commit after
including the module will continue to trigger the warning as expected.