fix merge

Author: nicolas-grekas

Tests/Fixtures/Validation/Article.php

@@ -2,7 +2,9 @@
 
 namespace Symfony\Bundle\FrameworkBundle\Tests\Fixtures\Validation;
 
-class Article implements NotExistingInterface
-{
-    public $category;
+if (!function_exists('__phpunit_run_isolated_test')) {
+    class Article implements NotExistingInterface
+    {
+        public $category;
+    }
 }