Distinguish asset read failures from unknown writes

internal/delivery/delivery.go

@@ -124,6 +124,9 @@ func Deliver(ctx context.Context, request Request) (Result, error) {
 	result.Conflicting = uploadResult.Conflicting
 	result.Uncertain = uploadResult.Uncertain
 	result.State = State(uploadResult.State)
+	if result.State == NotAttempted && releaseResult.WriteAttempted {
+		result.State = Partial
+	}
 	return result, uploadErr
 }