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

vendor/composer/installers/src/Composer/Installers/Symfony1Installer.php

@@ -0,0 +1,26 @@
+<?php
+namespace Composer\Installers;
+
+/**
+ * Plugin installer for symfony 1.x
+ *
+ * @author Jérôme Tamarelle <jerome@tamarelle.net>
+ */
+class Symfony1Installer extends BaseInstaller
+{
+    protected $locations = array(
+        'plugin'    => 'plugins/{$name}/',
+    );
+
+    /**
+     * Format package name to CamelCase
+     */
+    public function inflectPackageVars($vars)
+    {
+        $vars['name'] = preg_replace_callback('/(-[a-z])/', function ($matches) {
+            return strtoupper($matches[0][1]);
+        }, $vars['name']);
+
+        return $vars;
+    }
+}