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 (!CheckFinalTx(*this))
        return false;
    int nDepth = GetDepthInMainChain();
    if (nDepth >= 1)
        return true;
    if (nDepth < 0)
        return false;
    if (!bSpendZeroConfChange || !IsFromMe(ISMINE_ALL)) 
        return false;
    
    if (!InMempool())
        return false;
    
    BOOST_FOREACH(const CTxIn& txin, tx->vin)
    {
        
        const CWalletTx* parent = pwallet->GetWalletTx(txin.prevout.hash);
        if (parent == NULL)
            return false;
        const CTxOut& parentOut = parent->tx->vout[txin.prevout.n];
        if (pwallet->IsMine(parentOut) != ISMINE_SPENDABLE)
            return false;
    }
    return true;
}
bool CWalletTx::IsEquivalentTo(const CWalletTx& _tx) const