From 3ab88e02c7658a202f308b351982b38b80810975 Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Thu, 26 Feb 2015 12:58:01 +1100
Subject: [PATCH] delete from require.extensions when old extension handler is
 undefined

---
 src/babel/api/register/node.js | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/babel/api/register/node.js b/src/babel/api/register/node.js
index b89c6544b9..d494272a91 100644
--- a/src/babel/api/register/node.js
+++ b/src/babel/api/register/node.js
@@ -121,7 +121,11 @@ var registerExtension = function (ext) {
 
 var hookExtensions = function (_exts) {
   each(exts, function (old, ext) {
-    require.extensions[ext] = old;
+    if (old === undefined) {
+      delete require.extensions[ext];
+    } else {
+      require.extensions[ext] = old;
+    }
   });
 
   exts = {};