Update to drupal 8.0.0-rc1. For more information, see https://www.drupal.org/node/2582663

vendor/symfony/console/Tests/Fixtures/BarBucCommand.php

@@ -0,0 +1,11 @@
+<?php
+
+use Symfony\Component\Console\Command\Command;
+
+class BarBucCommand extends Command
+{
+    protected function configure()
+    {
+        $this->setName('bar:buc');
+    }
+}