Merge branch '2.8' into 3.4

* 2.8:
  [DI] fix dumping deprecated service in yaml
  bumped Symfony version to 2.8.43
  updated VERSION for 2.8.42
  update CONTRIBUTORS for 2.8.42
  updated CHANGELOG for 2.8.42

Author: nicolas-grekas

Dumper/YamlDumper.php

@@ -102,7 +102,7 @@ private function addService($id, Definition $definition)
         }
 
         if ($definition->isDeprecated()) {
-            $code .= sprintf("        deprecated: %s\n", $definition->getDeprecationMessage('%service_id%'));
+            $code .= sprintf("        deprecated: %s\n", $this->dumper->dump($definition->getDeprecationMessage('%service_id%')));
         }
 
         if ($definition->isAutowired()) {

Tests/Fixtures/config/prototype.expected.yml

@@ -10,7 +10,7 @@ services:
         tags:
             - { name: foo }
             - { name: baz }
-        deprecated: %service_id%
+        deprecated: '%service_id%'
         arguments: [1]
         factory: f
     Symfony\Component\DependencyInjection\Tests\Fixtures\Prototype\Sub\Bar:
@@ -19,7 +19,7 @@ services:
         tags:
             - { name: foo }
             - { name: baz }
-        deprecated: %service_id%
+        deprecated: '%service_id%'
         lazy: true
         arguments: [1]
         factory: f