imagetools: fix excessive copies on create command

Currently needed manifests were filtered out and then
copied in a loop, but for each copy still the full
unfiltered descriptor was copied instead of single
manifest, resulting multiple push attempts for same
descriptor.

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

commands/imagetools/create.go

@@ -208,7 +208,10 @@ func runCreate(ctx context.Context, dockerCli command.Cli, in createOptions, arg
 				for _, desc := range manifests {
 					eg2.Go(func() error {
 						sub.Log(1, fmt.Appendf(nil, "copying %s from %s to %s\n", desc.Digest.String(), desc.Source.Ref.String(), t.String()))
-						return r.Copy(ctx, desc.Source, t)
+						return r.Copy(ctx, &imagetools.Source{
+							Ref:  desc.Source.Ref,
+							Desc: desc.Descriptor,
+						}, t)
 					})
 				}
 				if err := eg2.Wait(); err != nil {