When no -config is set while committing, use the config of the base image

commands.go

@@ -736,8 +736,9 @@ func (srv *Server) CmdCommit(stdin io.ReadCloser, stdout io.Writer, args ...stri
 		return nil
 	}
 
-	config := &Config{}
+	var config *Config
 	if *flConfig != "" {
+		config = &Config{}
 		if err := json.Unmarshal([]byte(*flConfig), config); err != nil {
 			return err
 		}

graph.go

@@ -97,6 +97,11 @@ func (graph *Graph) Create(layerData Archive, container *Container, comment, aut
 		img.Parent = container.Image
 		img.Container = container.Id
 		img.ContainerConfig = *container.Config
+		if config == nil {
+			if parentImage, err := graph.Get(container.Image); err == nil && parentImage != nil {
+				img.Config = parentImage.Config
+			}
+		}
 	}
 	if err := graph.Register(layerData, img); err != nil {
 		return nil, err