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 (tx->vin.empty())
        return 0;
    CAmount debit = 0;
    if(filter & ISMINE_SPENDABLE)
    {
        if (fDebitCached)
            debit += nDebitCached;
        else
        {
            nDebitCached = pwallet->GetDebit(*this, ISMINE_SPENDABLE);
            fDebitCached = true;
            debit += nDebitCached;
        }
    }
    if(filter & ISMINE_WATCH_ONLY)
    {
        if(fWatchDebitCached)
            debit += nWatchDebitCached;
        else
        {
            nWatchDebitCached = pwallet->GetDebit(*this, ISMINE_WATCH_ONLY);
            fWatchDebitCached = true;
            debit += nWatchDebitCached;
        }
    }
    return debit;
}
CAmount CWalletTx::GetCredit(const isminefilter& filter) const