emberjs/ember.js — pull request #1682 by gabesmed (2013-01-04 23:22:05+00:00)
Title: Bugfix in SortableMixin; sortProperty observers not being correctly removed

Hi all, long-time observer, first time submitter here. Found a small bug (missing 'this' context in a forEach iterator) that was causing the observer for item sortProperty changes (contentItemSortPropertyDidChange) not to be correctly removed.

This should be the fix. Hope this is helpful!