Partial revert of https://golang.org/cl/20967 which
I can't reproduce and actually breaks me more.

Fixes #14901

Change-Id: I8cce443fbd95f5f6f2a5b6a4b9f2faab36167a12
Reviewed-on: https://go-review.googlesource.com/21292
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>