Fix broken integration test in 2.x [#4565 state:resolved]

Signed-off-by: NJosé Valim <jose.valim@gmail.com>

actionpack/lib/action_controller/integration.rb

@@ -355,6 +355,8 @@ def process(method, path, parameters = nil, headers = nil)
           # used in integration tests.
           @response.extend(TestResponseBehavior)
 
+          body.close if body.respond_to?(:close)
+
           return @status
         rescue MultiPartNeededException
           boundary = "----------XnJLe9ZIbbGUYtzPQJ16u1"