WithoutCancel returns a copy of parent that is not canceled when parent is canceled.
The returned context returns no Deadline or Err, and its Done channel is nil.
Calling Cause on the returned context returns nil.
API changes:
+pkg context, func WithoutCancel(Context) Context
Fixes#40221
Change-Id: Ide29631c08881176a2c2a58409fed9ca6072e65d
Reviewed-on: https://go-review.googlesource.com/c/go/+/479918
Run-TryBot: Sameer Ajmani <sameer@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
