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.
{
    AssertLockHeld(cs_wallet); 
    bool fCompressed = CanSupportFeature(FEATURE_COMPRPUBKEY); 
    CKey secret;
    
    int64_t nCreationTime = GetTime();
    CKeyMetadata metadata(nCreationTime);
    
    if (IsHDEnabled()) {
        DeriveNewChildKey(metadata, secret);
    } else {
        secret.MakeNewKey(fCompressed);
    }
    
    if (fCompressed)
        SetMinVersion(FEATURE_COMPRPUBKEY);
    CPubKey pubkey = secret.GetPubKey();
    assert(secret.VerifyPubKey(pubkey));
    mapKeyMetadata[pubkey.GetID()] = metadata;
    if (!nTimeFirstKey || nCreationTime < nTimeFirstKey)
        nTimeFirstKey = nCreationTime;
    if (!AddKeyPubKey(secret, pubkey))
        throw std::runtime_error(std::string(__func__) + ": AddKey failed");
    return pubkey;
}
void CWallet::DeriveNewChildKey(CKeyMetadata& metadata, CKey& secret)