[FrameworkBundle] Fix eager-loading of env vars in ConfigBuilderCache…

…Warmer

CacheWarmer/ConfigBuilderCacheWarmer.php

@@ -15,9 +15,12 @@
 use Symfony\Component\Config\Builder\ConfigBuilderGenerator;
 use Symfony\Component\Config\Builder\ConfigBuilderGeneratorInterface;
 use Symfony\Component\Config\Definition\ConfigurationInterface;
+use Symfony\Component\DependencyInjection\Container;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\DependencyInjection\Extension\ConfigurationExtensionInterface;
 use Symfony\Component\DependencyInjection\Extension\ExtensionInterface;
+use Symfony\Component\DependencyInjection\ParameterBag\ContainerBag;
+use Symfony\Component\DependencyInjection\ParameterBag\ParameterBag;
 use Symfony\Component\HttpKernel\CacheWarmer\CacheWarmerInterface;
 use Symfony\Component\HttpKernel\KernelInterface;
 
@@ -71,7 +74,8 @@ private function dumpExtension(ExtensionInterface $extension, ConfigBuilderGener
         if ($extension instanceof ConfigurationInterface) {
             $configuration = $extension;
         } elseif ($extension instanceof ConfigurationExtensionInterface) {
-            $configuration = $extension->getConfiguration([], new ContainerBuilder($this->kernel->getContainer()->getParameterBag()));
+            $container = $this->kernel->getContainer();
+            $configuration = $extension->getConfiguration([], new ContainerBuilder($container instanceof Container ? new ContainerBag($container) : new ParameterBag()));
         }
 
         if (!$configuration) {