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 (fChangeCached)
        return nChangeCached;
    nChangeCached = pwallet->GetChange(*this);
    fChangeCached = true;
    return nChangeCached;
}
bool CWalletTx::InMempool() const
{
    LOCK(mempool.cs);
    if (mempool.exists(GetHash())) {
        return true;
    }
    return false;
}
bool CWalletTx::IsTrusted() const