Merge pull request #1462 from DHager/document_transactional

Add a note to documentation for transactional()'s return values

docs/README.md

@@ -5,4 +5,13 @@
 1. Run ./bin/install-dependencies.sh
 2. Run ./bin/generate-docs.sh
 
-It will generate the documentation into the build directory of the checkout.
+It will generate the documentation into the build directory of the checkout.
+
+
+## Theme issues
+
+If you get a "Theme error", check if the `en/_theme` subdirectory is empty,
+in which case you will need to run:
+
+1. git submodule init
+2. git submodule update

docs/en/reference/transactions-and-concurrency.rst

@@ -98,6 +98,13 @@ functionally equivalent to the previously shown code looks as follows:
         $em->persist($user);
     });
 
+.. warning::
+
+    For historical reasons, ``EntityManager#transactional($func)`` will return
+    ``false`` whenever the return value of ``$func`` is loosely false.
+    Some examples of this include ``array()``, ``"0"``, ``""``, ``0``, and
+    ``null``.
+
 The difference between ``Connection#transactional($func)`` and
 ``EntityManager#transactional($func)`` is that the latter
 abstraction flushes the ``EntityManager`` prior to transaction