Automated change.

Fixes #15269

Change-Id: I8deb2ac0101d3f7c390467ceb0a1561b72edbb2f
Reviewed-on: https://go-review.googlesource.com/21962
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>