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.
{
    if (nIndex != -1)
        pwallet->ReturnKey(nIndex);
    nIndex = -1;
    vchPubKey = CPubKey();
}
void CWallet::GetAllReserveKeys(set<CKeyID>& setAddress) const
{
    setAddress.clear();
    CWalletDB walletdb(strWalletFile);
    LOCK2(cs_main, cs_wallet);
    BOOST_FOREACH(const int64_t& id, setKeyPool)
    {
        CKeyPool keypool;
        if (!walletdb.ReadPool(id, keypool))
            throw runtime_error(std::string(__func__) + ": read failed");
        assert(keypool.vchPubKey.IsValid());
        CKeyID keyID = keypool.vchPubKey.GetID();
        if (!HaveKey(keyID))
            throw runtime_error(std::string(__func__) + ": unknown key in key pool");
        setAddress.insert(keyID);
    }
}
void CWallet::UpdatedTransaction(const uint256 &hashTx)