Implemented checksum computation on image creation (necessary for new push primitive)

graph.go

@@ -98,11 +98,13 @@ 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
-			}
+		// FIXME: If an image is pulled from a raw URL (not created from a container),
+		// its checksum will not be computed, which will cause a push to fail
+		checksum, err := container.RwChecksum()
+		if err != nil {
+			return nil, err
 		}
+		img.Checksum = checksum
 	}
 	if err := graph.Register(layerData, img); err != nil {
 		return nil, err