appcelerator/titanium_mobile — pull request #1257 by sptramer (2012-01-25 19:43:24+00:00)
Title: [TIMOB-7362] Store 'nil' as an NSNull object in the props dict

This appears to be "classic" behavior and is something we need to be aware of; many properties require the ability to distinguish between "no property ever set" (technically undefined/nil) and "null stored" (null/NSNull).