Updates #18173

Change-Id: I4c667c89ba3bf16433a4cef7cb01054f1798667d
Reviewed-on: https://go-review.googlesource.com/33892
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>