Why mixNormalizedKey() just calls folly hasher() method again without considering the 'bits' argument?

[bgeng777]

I am learning the implementation of velox's hash table, but in the code, I find that the comments of mixNormalizedKey() says it is relevant to propagating bits but in the implementation, it just calls folly hasher() method.
Is there any magic thing I have not figured out?

Thanks.