Revert "export manifest for tar file (#1033)" (#1043)

This reverts commit f0ce227.

pkg/v1/tarball/image.go

@@ -117,22 +117,6 @@ type Descriptor struct {
 // Manifest represents the manifests of all images as the `manifest.json` file in a `docker save` tarball.
 type Manifest []Descriptor
 
-// LoadManifest load manifest
-func LoadManifest(opener Opener) (Manifest, error) {
-	m, err := opener()
-	if err != nil {
-		return nil, err
-	}
-	defer m.Close()
-
-	var manifest Manifest
-
-	if err := json.NewDecoder(m).Decode(&manifest); err != nil {
-		return nil, err
-	}
-	return manifest, nil
-}
-
 func (m Manifest) findDescriptor(tag *name.Tag) (*Descriptor, error) {
 	if tag == nil {
 		if len(m) != 1 {