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

vendor/guzzlehttp/guzzle/src/Exception/ConnectException.php

@@ -0,0 +1,37 @@
+<?php
+namespace GuzzleHttp\Exception;
+
+use Psr\Http\Message\RequestInterface;
+
+/**
+ * Exception thrown when a connection cannot be established.
+ *
+ * Note that no response is present for a ConnectException
+ */
+class ConnectException extends RequestException
+{
+    public function __construct(
+        $message,
+        RequestInterface $request,
+        \Exception $previous = null,
+        array $handlerContext = []
+    ) {
+        parent::__construct($message, $request, null, $previous, $handlerContext);
+    }
+
+    /**
+     * @return null
+     */
+    public function getResponse()
+    {
+        return null;
+    }
+
+    /**
+     * @return bool
+     */
+    public function hasResponse()
+    {
+        return false;
+    }
+}