Feature request from mage2pro, posted on GitHub Nov 02, 2015
The problem line is
https://github.com/magento/magento2/blob/f578e54e093c31378ca981cfe336f7e651194585/app/code/Magento/C...
I propose to change it to
if (!$this->dataProcessor->validate($model->getData())) {
My detailed explanation: https://mage2.pro/t/159