From 9e2fc6db9c42c07e6d923a838486e7a2cc1f4b7f Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Tue, 11 Nov 2014 01:04:39 +1100
Subject: [PATCH] clone options - sindresorhus/grunt-6to5#7

---
 lib/6to5/file.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/6to5/file.js b/lib/6to5/file.js
index 9e8d6a674b..30d35e56c8 100644
--- a/lib/6to5/file.js
+++ b/lib/6to5/file.js
@@ -21,7 +21,7 @@ function File(opts) {
 File.declarations = ["extends", "class-props", "slice"];
 
 File.normaliseOptions = function (opts) {
-  opts = opts || {};
+  opts = _.cloneDeep(opts || {});
 
   _.defaults(opts, {
     whitespace: true,