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.
{
    LOCK(cs_wallet);
    
    if (setKeyPool.empty())
        return GetTime();
    
    CKeyPool keypool;
    CWalletDB walletdb(strWalletFile);
    int64_t nIndex = *(setKeyPool.begin());
    if (!walletdb.ReadPool(nIndex, keypool))
        throw runtime_error(std::string(__func__) + ": read oldest key in keypool failed");
    assert(keypool.vchPubKey.IsValid());
    return keypool.nTime;
}
std::map<CTxDestination, CAmount> CWallet::GetAddressBalances()