Fixes #27990

Change-Id: I0f09fc6f68cec770b1c26eed2315afbf6bf6cd4d
GitHub-Last-Rev: 8486e6d5019c6c21b10e5fcf10a2727cf2705174
GitHub-Pull-Request: golang/go#27991
Reviewed-on: https://go-review.googlesource.com/c/139417
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>