t/hijack.ru in rainbows-5.1.1 vs t/hijack.ru in rainbows-5.2.0

@@ -43,12 +43,12 @@
   when "/hijack_res"
     r = "response.hijacked"
     [ 200,
       {
         "Content-Length" => r.bytesize.to_s,
-        "rack.hijack" => proc do |io|
-          io.write(r)
-          lazy_close(io)
+        "rack.hijack" => proc do |sock|
+          sock.write(r)
+          lazy_close(sock)
         end
       },
       DieIfUsed.new
     ]
   end