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.
"\nNow we can so something like sign\n"
            + HelpExampleCli("signmessage", "\"address\" \"test message\"") +
            "\nNow lock the wallet again by removing the passphrase\n"
            + HelpExampleCli("walletlock", "") +
            "\nAs a json rpc call\n"
            + HelpExampleRpc("encryptwallet", "\"my pass phrase\"")
        );
    LOCK2(cs_main, pwalletMain->cs_wallet);
    if (request.fHelp)
        return true;
    if (pwalletMain->IsCrypted())
        throw JSONRPCError(RPC_WALLET_WRONG_ENC_STATE, "Error: running with an encrypted wallet, but encryptwallet was called.");
    
    
    SecureString strWalletPass;
    strWalletPass.reserve(100);
    strWalletPass = request.params[0].get_str().c_str();
    if (strWalletPass.length() < 1)
        throw runtime_error(
            "encryptwallet <passphrase>\n"
            "Encrypts the wallet with <passphrase>.");
    if (!pwalletMain->EncryptWallet(strWalletPass))
        throw JSONRPCError(RPC_WALLET_ENCRYPTION_FAILED, "Error: Failed to encrypt the wallet.");
    
    
    
    StartShutdown();
    return "wallet encrypted; Bitcoin server stopping, restart to run with encrypted wallet. The keypool has been flushed and a new HD seed was generated (if you are using HD). You need to make a new backup.";
}
UniValue lockunspent(const JSONRPCRequest& request)