plumbing: format/packfile, add SaveOriginalMetadata function

Signed-off-by: Javi Fontan <jfontan@gmail.com>

Author: jfontan

plumbing/format/packfile/delta_selector.go

@@ -231,7 +231,7 @@ func (dw *deltaSelector) walk(
 			delete(indexMap, obj.Hash())
 
 			if obj.IsDelta() {
-				obj.SetOriginal(obj.Original)
+				obj.SaveOriginalMetadata()
 				obj.CleanOriginal()
 			}
 		}

plumbing/format/packfile/object_pack.go

@@ -81,11 +81,15 @@ func (o *ObjectToPack) WantWrite() bool {
 // is nil Original is set but previous resolved values are kept
 func (o *ObjectToPack) SetOriginal(obj plumbing.EncodedObject) {
 	o.Original = obj
+	o.SaveOriginalMetadata()
+}
 
-	if obj != nil {
-		o.originalSize = obj.Size()
-		o.originalType = obj.Type()
-		o.originalHash = obj.Hash()
+// SaveOriginalMetadata saves size, type and hash of Original object
+func (o *ObjectToPack) SaveOriginalMetadata() {
+	if o.Original != nil {
+		o.originalSize = o.Original.Size()
+		o.originalType = o.Original.Type()
+		o.originalHash = o.Original.Hash()
 		o.resolvedOriginal = true
 	}
 }