Cloning of model is unsafe.

[romaninsh]

I defined model like this:

class Model_Transfer extends Model {
    public $table='doc';
    function init() {
        parent::init();

        $this->addField('amount');
        $this->pmt = $this->join('payment.doc_id');

        $this->pmt->hasOne('account_id', 'Model_Account');
        $this->pmt->hasOne('tronsfer_payment_id', 'Model_Transfer');        
    }

    function createPayment($account2, $amount)
    {
        $leg2 = clone $this;
        $leg2['account_id'] = $account2->id;
        $leg2['amount'] = $amount;
        $leg2->save();

        $this['amount'] = -$amount;
        $this['transfer_payment_id'] = $leg2->id;
        $this->save();

        $leg2['transfer_payment_id'] = $this->id;
        $leg2->save();  // BUG IN THIS LINE
    }
}

The bug happens in the last save. It appears due to the cloning of a model, the related record ID gets messed up and instead of updating leg2's transfer_payment_id AD actually updates the other record.

If `clone` is replaced with 'new' then no problems appear. 

Clone must be made safe.

 - [ ] Implement a tes-case for thi scase
 - [ ] fix

[romaninsh]

fixed in #107