Just short and sweet, can a druid do this to themself with the Nature Staff before wild shaping?
I'm inclined to believe it's still no, even after errata?
A druid can certainly cast magic fang on themselves, now that it doesn't specify "ally."
But if you then wild shape you'll lose the benefit, because it's attached to a specific unarmed attack of the form you had when you received the spell, and you won't have that particular attack any more.