Unit Price is always 0 if there is combination price available_date_attribute

[Bao NGUYEN]

It can't update the unit_ratio and unit price of a product on the back office,

It works if there is not date available  in combination, if there is date , the unit price has been reset to 0.

I debug and i found out why it's becaus of this code in the product class. it will update the product with combinntion information. For me it doesn't make sense

 public function setAvailableDate($available_date = '0000-00-00')
    {
        if (Validate::isDateFormat($available_date) && $this->available_date != $available_date) {
            $this->available_date = $available_date;

            return $this->update();
        }