Read staged metadata from the staged dir

Change-Id: I630cd3193f7c7267238b06ad948ef5e70da666ed
diff --git a/local_store.go b/local_store.go
index 00cea4a..68cb609 100644
--- a/local_store.go
+++ b/local_store.go
@@ -161,7 +161,7 @@
 	meta := make(map[string]json.RawMessage)
 	var err error
 	for _, name := range topLevelManifests {
-		path := filepath.Join(f.repoDir(), name)
+		path := filepath.Join(f.stagedDir(), name)
 		if _, err := os.Stat(path); os.IsNotExist(err) {
 			continue
 		}