jashkenas/backbone — pull request #2723 by metafeather (2013-08-14 14:04:00+00:00)
Title: Fix #2719 - Check Collection.add will only merge or delete existing Back...

...bone Models in its cache

Mitigated now Collection.add default behaviour has been changed since v1.0.0 to {merge: false}, a Collection does not check that it gets an actual Backbone Model from the cache before attempting to merge.