use cached images instead of fetching the same image again

Docker-DCO-1.1-Signed-off-by: Daniel, Dao Quang Minh <dqminh89@gmail.com> (github: dqminh)

daemon/daemon.go

@@ -1090,9 +1090,9 @@ func (daemon *Daemon) ImageGetCached(imgID string, config *runconfig.Config) (*i
 	// Loop on the children of the given image and check the config
 	var match *image.Image
 	for elem := range imageMap[imgID] {
-		img, err := daemon.Graph().Get(elem)
-		if err != nil {
-			return nil, err
+		img, ok := images[elem]
+		if !ok {
+			return nil, fmt.Errorf("unable to find image %q", elem)
 		}
 		if runconfig.Compare(&img.ContainerConfig, config) {
 			if match == nil || match.Created.Before(img.Created) {