Currently, the function is_invalid_use_of_sighash_single() is incompatible with Bitcoin Core’s implementation. I discovered this issue while working on an experimental Rust Bitcoin script interpreter, where it failed to verify the signature for the following transaction input using the sighash calculated from legacy_signature_hash():

block_number: 479902, 
tx_index: 1139, 
txid: 1395dde8ec0152f4cb090f4d4e8dcb14cc0d8bbba780e686c44934370cd316ec
input_index: 2

sighash for this specific input is 131(0x83), input_index is 2, outputs_len is 2, it's a single sighash bug per Bitcoin Core.

However, 131 is interpreted as EcdsaSighashType::SinglePlusAnyoneCanPay here, is_invalid_use_of_sighash_single() handles EcdsaSighashType::Single only, thus it's not considered as sighash_single_bug and legavy_signature_hash() does not return the expected sighash ONE.

This results in an incorrect outcome that diverges from Bitcoin Core’s behavior, and makes the comment in legacy_signature_hash() misleading, as it claims the behavior is compatible.