MAGETWO-55908: Prepare PR

Author: Yaroslav Onischenko

dev/tests/functional/tests/app/Magento/Sales/Test/Block/Adminhtml/Order/Grid.php

@@ -96,7 +96,7 @@ public function getPurchasePointStoreGroups()
         $this->openFilterBlock();
 
         $storeGroupElements = $this->_rootElement->find($this->filters['purchase_point']['selector'])
-            ->getElements('//option/preceding-sibling::optgroup[1]', Locator::SELECTOR_XPATH);
+            ->getElements('.//option/preceding-sibling::optgroup[1]', Locator::SELECTOR_XPATH);
         $result = [];
 
         foreach ($storeGroupElements as $storeGroupElement) {