Function fnv1a64_hex 

pub fn fnv1a64_hex(bytes: &[u8]) -> String

FNV-1a (64-bit) over bytes, as 16 lowercase hex chars — contract_hash’s algorithm over raw bytes. #1883, slice 1b also uses it for an asset’s content hash (assets::served_path), where the same reasoning holds: it only has to tell one project’s own files apart, reproducibly.