Merge branch '4.4'

* 4.4:
  [HttpKernel] fix merge
  fix tests
  [HttpClient] fix throwing HTTP exceptions when the 1st chunk is emitted

Author: nicolas-grekas

Tests/Mapping/Factory/LazyLoadingMetadataFactoryTest.php

@@ -15,6 +15,7 @@
 use Psr\Cache\CacheItemPoolInterface;
 use Symfony\Component\Cache\Adapter\ArrayAdapter;
 use Symfony\Component\Validator\Constraints\Callback;
+use Symfony\Component\Validator\Mapping\Cache\Psr6Cache;
 use Symfony\Component\Validator\Mapping\ClassMetadata;
 use Symfony\Component\Validator\Mapping\Factory\LazyLoadingMetadataFactory;
 use Symfony\Component\Validator\Mapping\Loader\LoaderInterface;