Fixes #17754
Updates #9478 (details in here)

Change-Id: Iae2c1ca05a18ed266b53b2594c22fc57fab33c5e
Reviewed-on: https://go-review.googlesource.com/32587
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>