Fixes #19850

Change-Id: I8c86e288159408c687c2a85f458ade282adae450
Reviewed-on: https://go-review.googlesource.com/45077
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>