Sync with golang/tour@a4d680413ab45695cc2c6c3e232d508aeb637f25.
Sync with golang/tour@a4d680413ab45695cc2c6c3e232d508aeb637f25.

shuLhan/tour,shuLhan/go-tour-id,shuLhan/tour,shuLhan/go-tour-id,shuLhan/go-tour-id,shuLhan/tour