https://github.com/ethereum/eth-hash/commit/99d647e9832f12672c52556dbb21b4c38a75c35d makes Keccak256 keep a reference to the backend module (e.g. eth_hash.backends.pycryptodome) whereas before it'd keep references to the backend's functions (keccak256 and preimage). That is a problem because it means Keccak256 is no longer picklable, which means we can't use it with, say, a concurrent.futures.ProcessPoolExecutor
https://github.com/ethereum/eth-hash/commit/99d647e9832f12672c52556dbb21b4c38a75c35d makes
Keccak256keep a reference to the backend module (e.g.eth_hash.backends.pycryptodome) whereas before it'd keep references to the backend's functions (keccak256andpreimage). That is a problem because it meansKeccak256is no longer picklable, which means we can't use it with, say, aconcurrent.futures.ProcessPoolExecutor