subclass to base class but not subclass pointer to base class pointer?

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Why can D implicitly cast from the subclass to the base class, 
but not implicitly from the subclasse pointer to the base class 
pointer?

This works: http://dpaste.1azy.net/30dd34a0
This not: http://dpaste.1azy.net/ffacfd83

Makes not much sense for me.