Triggering rollback when entitystate is changed from modified to unchanged

With this change, EF rejects pending changes on a tracked entity when it's status is changed from Modified to Unchanged.  
I think it would be good to only set the property if the original value is different from the current value since setting a property may trigger both change tracking behaviors in our code or validation, etc. code in the entity. Also, as Rowan pointed out a few minutes ago, usually the original values and the current values will be the same.