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

Command/ServerStartCommand.php

@@ -159,5 +159,7 @@ protected function execute(InputInterface $input, OutputInterface $output)
 
             return 1;
         }
+
+        return null;
     }
 }

Command/ServerStatusCommand.php

@@ -98,5 +98,7 @@ protected function execute(InputInterface $input, OutputInterface $output)
                 return 1;
             }
         }
+
+        return null;
     }
 }

Command/ServerStopCommand.php

@@ -72,5 +72,7 @@ protected function execute(InputInterface $input, OutputInterface $output)
 
             return 1;
         }
+
+        return null;
     }
 }