dumping stack trace on direct deprecation

Author: weaverryan

.travis.yml

@@ -31,7 +31,7 @@ before_install:
     - composer update
 
 install:
-    - ./vendor/bin/simple-phpunit install
+    - SYMFONY_DEPRECATIONS_HELPER='/Doctrine\\Common\\Persistence\\Mapping\\Driver\\MappingDriverChain class is deprecated/' ./vendor/bin/simple-phpunit install
 
 script:
     - composer validate --strict --no-check-lock