Merge branch '3.4' into 4.2

* 3.4:
  fix Debug component dependencies
  [travis] not all components have a master branch

Author: xabbuh

composer.json

@@ -21,6 +21,7 @@
         "symfony/cache": "~4.2",
         "symfony/config": "~4.2",
         "symfony/contracts": "^1.0.2",
+        "symfony/debug": "~4.0",
         "symfony/dependency-injection": "^4.2.5",
         "symfony/event-dispatcher": "^4.1",
         "symfony/http-foundation": "^4.2.5",