added a (passing) test for github issue #208: coroutine as iterator doesn't work
added a (passing) test for github issue #208: coroutine as iterator doesn't work

yeahdongcn/SEnginx,yeahdongcn/SEnginx,yeahdongcn/SEnginx,yeahdongcn/SEnginx,yeahdongcn/SEnginx,yeahdongcn/SEnginx,yeahdongcn/SEnginx