powmedia/backbone-deep-model — pull request #19 by mikefrey (2012-07-03 03:07:28+00:00)
Title: Setting a deep property to the same value deletes the property

Fixed the issue originally reported by @jessehouchins

Here is an example that shows the issue.
http://jsfiddle.net/cVAd6/1/

Updated fiddle pointing to my fork: http://jsfiddle.net/cVAd6/2/