Merge branch '3.4' into 4.3

* 3.4:
  Fix inconsistent return points.
  [Security/Core] UserInterface::getPassword() can return null
  [Router] Fix TraceableUrlMatcher behaviour with trailing slash

Author: nicolas-grekas

Tests/Fixtures/TestClassMagicCall.php

@@ -33,5 +33,7 @@ public function __call($method, array $args)
         if ('setMagicCallProperty' === $method) {
             $this->magicCallProperty = reset($args);
         }
+
+        return null;
     }
 }