container/init: ignore finished process

This is not considered an error, if the process finishes while the signal is being delivered.

Signed-off-by: Ophestra <cat@gensokyo.uk>

container/init.go

@@ -495,7 +495,7 @@ func initEntrypoint(k syscallDispatcher, msg message.Msg) {
 		case s := <-sig:
 			if s == CancelSignal && params.ForwardCancel && cmd.Process != nil {
 				msg.Verbose("forwarding context cancellation")
-				if err := k.signal(cmd, os.Interrupt); err != nil {
+				if err := k.signal(cmd, os.Interrupt); err != nil && !errors.Is(err, os.ErrProcessDone) {
 					k.printf(msg, "cannot forward cancellation: %v", err)
 				}
 				continue