Merge branch '3.4' into 4.4

* 3.4:
  [Form] Better explicit cloning with "by_reference" option

Author: javiereguiluz

reference/forms/types/options/by_reference.rst.inc

@@ -41,8 +41,8 @@ If you set ``by_reference`` to false, submitting looks like this::
     $author->setEmail('...');
     $article->setAuthor($author);
 
-So, all that ``by_reference=false`` really does is force the framework to
-call the setter on the parent object.
+So, all that ``by_reference=false`` really does is that it clones the object,
+which enforces the framework to call the setter on the parent object.
 
 Similarly, if you're using the :doc:`CollectionType </reference/forms/types/collection>`
 field where your underlying collection data is an object (like with