Too many sha256 rounds?

[d18c7db]

Why is the multithreaded miner doing quadruple sha256 rounds as per line 133

hash_result = hashlib.sha256(hashlib.sha256(hashlib.sha256(hashlib.sha256(block_header + nonce_bin).digest()).digest()).digest()).digest()

Is it really correct? Bitcoin hash generation clearly specifies only double sha256.

[HugoXOX3]

Thanks for that,indeed I make a mistake on that