return the not found error

selector/cache/cache.go

@@ -119,10 +119,20 @@ func (c *cacheSelector) get(service string) ([]*registry.Service, error) {
 	}
 
 	// expired entry so get service
-	if services, err := get(service); err == nil {
+	services, err := get(service)
+
+	// no error then return error
+	if err == nil {
 		return services, nil
 	}
 
+	// not found error then return
+	if err == registry.ErrNotFound {
+		return nil, selector.ErrNotFound
+	}
+
+	// other error
+
 	// return expired cache as last resort
 	return c.cp(services), nil
 }