MAGETWO-56778: Value for multiple select attribute does not save

Author: vnayda

app/code/Magento/Catalog/Model/ResourceModel/Product.php

@@ -567,7 +567,7 @@ public function validate($object)
      */
     public function load($object, $entityId, $attributes = [])
     {
-        $this->loadAttributesMetadata($attributes, $object);
+        $this->loadAttributesMetadata($attributes);
         $this->getEntityManager()->load($object, $entityId);
         return $this;
     }

app/code/Magento/Eav/Model/Entity/AbstractEntity.php

@@ -975,13 +975,12 @@ public function load($object, $entityId, $attributes = [])
      * Loads attributes metadata.
      *
      * @param array|null $attributes
-     * @param null|\Magento\Framework\DataObject $object
      * @return $this
      */
-    protected function loadAttributesMetadata($attributes, $object = null)
+    protected function loadAttributesMetadata($attributes)
     {
         if (empty($attributes)) {
-            $this->loadAllAttributes($object);
+            $this->loadAllAttributes();
         } else {
             if (!is_array($attributes)) {
                 $attributes = [$attributes];

app/code/Magento/Eav/Model/Entity/Attribute.php

@@ -498,6 +498,7 @@ public function getIdentities()
      */
     public function __sleep()
     {
+        $this->unsetData('attribute_set_info');
         return array_diff(
             parent::__sleep(),
             ['_localeDate', '_localeResolver', 'reservedAttributeList', 'dateTimeFormatter']

lib/internal/Magento/Framework/EntityManager/Observer/AfterEntitySave.php

@@ -27,9 +27,6 @@ public function execute(Observer $observer)
     {
         $entity = $observer->getEvent()->getEntity();
         if ($entity instanceof AbstractModel) {
-            if (method_exists($entity->getResource(), 'loadAllAttributes')) {
-                $entity->getResource()->loadAllAttributes($entity);
-            }
             $entity->getResource()->afterSave($entity);
             $entity->afterSave();
             $entity->getResource()->addCommitCallback([$entity, 'afterCommitCallback']);