An atomic.Bool isn't necessary here since, unless otherwise
specified, the methods of an object are not concurrency-safe
w.r.t. each other. Using an atomic causes the copylocks vet
check to warn about copying of Cmd, which is not wrong, because
one shouldn't be copying opaque complex structs from other
packages, but it is a nuisance in the absence of any safe way
to copy a Cmd.
If and when we add a Clone method to Cmd (see #77075) then
it would be appropriate to revert this change so that we get
the benefit of the static check (though ideally we would make
a more explicit tool-readable declaration of the "do not copy"
attribute than merely happening to use an atomic.Bool).
For #77075
Change-Id: I982d4e86623ca165a3e76bbf648fd44041d5f6bb
Reviewed-on: https://go-review.googlesource.com/c/go/+/734200 Reviewed-by: Michael Pratt <mpratt@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>