fix tweak bug whereby 00...00:0 and 00...00:255 both produce 00...00 by replacing it with a function that just writes the first 4 bytes to the hash value always.
fix tweak bug whereby 00...00:0 and 00...00:255 both produce 00...00 by
replacing it with a function that just writes the first 4 bytes to the
hash value always.

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