If I unlock an encrypted wallet for 359711509437336256 or less seconds, I can sign transactions with it:

    $ bitcoin-cli walletpassphrase "$x" 359711509437336256
    $ echo $?
    0
    $ bitcoin-cli signrawtransaction $tx | grep complete
      "complete": true

But if I unlock it for 359711509437336257 or more seconds, it appears to have unlocked but I can't sign any transactions:

    $ bitcoin-cli walletpassphrase "$x" 359711509437336257
    $ echo $?
    0
    $ bitcoin-cli signrawtransaction $tx | grep complete
    error code: -13
    error message:
    Error: Please enter the wallet passphrase with walletpassphrase first.

I don't know the significance of that number. It's nowhere near a power of 2.

I was trying to unlock the wallet effectively "forever", so put a big number. If I use too big a number (2^63 or more) I get an error message `JSON integer out of range` but for numbers between 359711509437336257 and 2^63-1 inclusive I get no error, but no actual unlocking.
}
        if (options.exists("replaceable")) {
            coin_control.signalRbf = options["replaceable"].get_bool();
        }
        if (options.exists("estimate_mode")) {
            if (!FeeModeFromString(options["estimate_mode"].get_str(), coin_control.m_fee_mode)) {
                throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid estimate_mode parameter");
            }
        }
    }
    
    
    pwallet->BlockUntilSyncedToCurrentChain();
    LOCK2(cs_main, pwallet->cs_wallet);
    EnsureWalletIsUnlocked(pwallet);
    std::vector<std::string> errors;
    CAmount old_fee;
    CAmount new_fee;
    CMutableTransaction mtx;
    feebumper::Result res = feebumper::CreateTransaction(pwallet, hash, coin_control, totalFee, errors, old_fee, new_fee, mtx);
    if (res != feebumper::Result::OK) {
        switch(res) {
            case feebumper::Result::INVALID_ADDRESS_OR_KEY:
                throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, errors[0]);
                break;
            case feebumper::Result::INVALID_REQUEST:
                throw JSONRPCError(RPC_INVALID_REQUEST, errors[0]);
                break;
            case feebumper::Result::INVALID_PARAMETER:
                throw JSONRPCError(RPC_INVALID_PARAMETER, errors[0]);