If one calls `fundrawtransaction`, the change address will be retrieved from the keypool, though, this key/address will always be returned to the pool, leading to the problem that the next `getnewaddress()` call will restult in the same key/address.

Either we remove the auto-change-address (users would need to call `getrawchangeaddress` first [current best practice anyway]) or we add a call to keep/mark a specific key/address as change (after one have sent the funded raw transaction).

Reported by @NicolasDorier on IRC.
UniValue o(UniValue::VOBJ);
        o.push_back(Pair("txid", outpt.hash.GetHex()));
        o.push_back(Pair("vout", (int)outpt.n));
        ret.push_back(o);
    }
    return ret;
}
UniValue settxfee(const JSONRPCRequest& request)
{
    if (!EnsureWalletIsAvailable(request.fHelp))
        return NullUniValue;
    if (request.fHelp || request.params.size() < 1 || request.params.size() > 1)
        throw runtime_error(
            "settxfee amount\n"
            "\nSet the transaction fee per kB. Overwrites the paytxfee parameter.\n"
            "\nArguments:\n"
            "1. amount         (numeric or string, required) The transaction fee in " + CURRENCY_UNIT + "/kB\n"
            "\nResult\n"
            "true|false        (boolean) Returns true if successful\n"
            "\nExamples:\n"
            + HelpExampleCli("settxfee", "0.00001")
            + HelpExampleRpc("settxfee", "0.00001")
        );
    LOCK2(cs_main, pwalletMain->cs_wallet);
    
    CAmount nAmount = AmountFromValue(request.params[0]);
    payTxFee = CFeeRate(nAmount, 1000);
    return true;
}
UniValue getwalletinfo(const JSONRPCRequest& request)