I kind of suck at boolean algebra, but:
https://github.com/bitcoin/bitcoin/blob/37612099ec7314b15a07d8bac55161ed4e8e7491/src/rpc/rawtransaction.cpp#L1672


Unless I'm mistaken (which is highly likely) the whole thing can't work  (except the edge case where `permitsigdata=true` and you have no sig data) 
UniValue txids = request.params[0].get_array();
    for (unsigned int idx = 0; idx < txids.size(); idx++) {
        const UniValue& txid = txids[idx];
        uint256 hash(ParseHashV(txid, "txid"));
        if (setTxids.count(hash))
            throw JSONRPCError(RPC_INVALID_PARAMETER, std::string("Invalid parameter, duplicated txid: ")+txid.get_str());
       setTxids.insert(hash);
       oneTxid = hash;
    }
    CBlockIndex* pblockindex = nullptr;
    uint256 hashBlock;
    if (!request.params[1].isNull()) {
        LOCK(cs_main);
        hashBlock = ParseHashV(request.params[1], "blockhash");
        pblockindex = LookupBlockIndex(hashBlock);
        if (!pblockindex) {
            throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Block not found");
        }
    } else {
        LOCK(cs_main);
        
        for (const auto& tx : setTxids) {
            const Coin& coin = AccessByTxid(*pcoinsTip, tx);
            if (!coin.IsSpent()) {
                pblockindex = chainActive[coin.nHeight];
                break;
            }
        }
    }