From da11cf8f9f26f39a2f0e77fb0777c21194f91605 Mon Sep 17 00:00:00 2001
From: jettcalleja <jettcalleja@gmail.com>
Date: Mon, 2 Oct 2017 21:54:46 +0800
Subject: [PATCH] fix: clone() cloning prototype's custom methods

---
 lib/winston/common.js | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/lib/winston/common.js b/lib/winston/common.js
index d1af9491f..fe0e1dacc 100644
--- a/lib/winston/common.js
+++ b/lib/winston/common.js
@@ -104,17 +104,19 @@ function clone(obj) {
   var copy = Array.isArray(obj) ? [] : {};
 
   for (var i in obj) {
-    if (Array.isArray(obj[i])) {
-      copy[i] = obj[i].slice(0);
-    }
-    else if (obj[i] instanceof Buffer) {
+    if (obj.hasOwnProperty(i)) {
+      if (Array.isArray(obj[i])) {
         copy[i] = obj[i].slice(0);
-    }
-    else if (typeof obj[i] != 'function') {
-      copy[i] = obj[i] instanceof Object ? exports.clone(obj[i]) : obj[i];
-    }
-    else if (typeof obj[i] === 'function') {
-      copy[i] = obj[i];
+      }
+      else if (obj[i] instanceof Buffer) {
+        copy[i] = obj[i].slice(0);
+      }
+      else if (typeof obj[i] != 'function') {
+        copy[i] = obj[i] instanceof Object ? exports.clone(obj[i]) : obj[i];
+      }
+      else if (typeof obj[i] === 'function') {
+        copy[i] = obj[i];
+      }
     }
   }