MAGETWO-44584: Error "The stock item for Product in option is not valid." when adding configurable product on second website

Author: aohorodnyk

app/code/Magento/CatalogInventory/Model/StockRegistryProvider.php

@@ -148,7 +148,7 @@ public function getStockItem($productId, $websiteId)
         if (!isset($this->stockItems[$key])) {
             $criteria = $this->stockItemCriteriaFactory->create();
             $criteria->setProductsFilter($productId);
-            $criteria->setWebsiteFilter($websiteId);
+            //$criteria->setWebsiteFilter($websiteId);
             $collection = $this->stockItemRepository->getList($criteria);
             $stockItem = current($collection->getItems());
             if ($stockItem && $stockItem->getItemId()) {

app/code/Magento/CatalogInventory/Test/Unit/Model/Spi/StockRegistryProviderTest.php

@@ -253,7 +253,7 @@ public function testGetStock()
     public function testGetStockItem()
     {
         $this->stockItemCriteriaFactory->expects($this->once())->method('create')->willReturn($this->stockItemCriteria);
-        $this->stockItemCriteria->expects($this->once())->method('setWebsiteFilter')->willReturn(null);
+        //$this->stockItemCriteria->expects($this->once())->method('setWebsiteFilter')->willReturn(null);
         $this->stockItemCriteria->expects($this->once())->method('setProductsFilter')->willReturn(null);
         $stockItemCollection = $this->getMock(
             '\Magento\CatalogInventory\Model\ResourceModel\Stock\Item\Collection',