os: export ErrProcessDone variable in windows and plan9
Exposes ErrProcessDone variable in windows and plan9
also returns this error code instead of
errors.New("os: process already finished")
Fixes #42311
Change-Id: Ie807b6526e7b6c27636e6bffe5ff0c904b319be4
GitHub-Last-Rev:
2153e0d7020d8ee9e94087d02977ea049b7fd6a0
GitHub-Pull-Request: golang/go#42313
Reviewed-on: https://go-review.googlesource.com/c/go/+/266997
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Dmitri Shuralyov <dmitshur@golang.org>