Index: src/wp-admin/js/theme.js
===================================================================
--- src/wp-admin/js/theme.js	(revision 27501)
+++ src/wp-admin/js/theme.js	(working copy)
@@ -47,7 +47,7 @@
 		this.set({
 			installURI: install,
 			previewURI: preview,
-			id: this.get( 'slug' )
+			id: this.get( 'slug' ) || this.get( 'id' )
 		});
 	}
 });