See also golang-dev discussion:
https://groups.google.com/d/msg/golang-dev/Nk9gnTINlTg/SV8rBt-2__kJ

Change-Id: I49edd98d73400c1757b6085dec86752de569c01a
Reviewed-on: https://go-review.googlesource.com/8923Reviewed-by: Rob Pike <r@golang.org>