Merge branch '4.1'

* 4.1:
  [Config] minor fix that removes a PHP 7.3 deprecation
  [Translation] fix perf of lint:xliff command

src/Symfony/Component/Config/Definition/BaseNode.php

@@ -499,7 +499,7 @@ abstract class BaseNode implements NodeInterface
                 return self::$placeholders[$value];
             }
 
-            if (0 === strpos($value, self::$placeholderUniquePrefix)) {
+            if (self::$placeholderUniquePrefix && 0 === strpos($value, self::$placeholderUniquePrefix)) {
                 return array();
             }
         }