Copy changes made to $this->data in beforeValidate callbacks

lib/Cake/Model/Model.php

@@ -2178,6 +2178,7 @@ public function saveAssociated($data = null, $options = array()) {
 
 		if ($options['validate'] === 'first') {
 			$validates = $this->validateAssociated($data, $options);
+			$data = $this->data;
 			if ((!$validates && $options['atomic']) || (!$options['atomic'] && in_array(false, $validates, true))) {
 				return $validates;
 			}