Merge pull request moby#4587 from jedevc/use-errors-is

solver: use errors.Is when checking context.Cause()

Author: tonistiigi

solver/errdefs/context.go

@@ -14,7 +14,7 @@ func IsCanceled(ctx context.Context, err error) bool {
 		return true
 	}
 	// grpc does not set cancel correctly when stream gets cancelled and then Recv is called
-	if err != nil && context.Cause(ctx) == context.Canceled {
+	if err != nil && errors.Is(context.Cause(ctx), context.Canceled) {
 		// when this error comes from containerd it is not typed at all, just concatenated string
 		if strings.Contains(err.Error(), "EOF") {
 			return true