From a8d368906128c6509dd4ac7362221a81c4a31bbf Mon Sep 17 00:00:00 2001
From: John-David Dalton <john.david.dalton@gmail.com>
Date: Sat, 2 Jul 2016 10:19:15 -0700
Subject: [PATCH] Ensure `_.isEqual` works more consistently with circular
 references.

---
 lodash.js | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lodash.js b/lodash.js
index df54e5df5..802ee06dd 100644
--- a/lodash.js
+++ b/lodash.js
@@ -5230,7 +5230,7 @@
       }
       // Assume cyclic values are equal.
       var stacked = stack.get(array);
-      if (stacked) {
+      if (stacked && stack.get(other)) {
         return stacked == other;
       }
       var index = -1,
@@ -5238,6 +5238,7 @@
           seen = (bitmask & UNORDERED_COMPARE_FLAG) ? new SetCache : undefined;
 
       stack.set(array, other);
+      stack.set(other, array);
 
       // Ignore non-index properties.
       while (++index < arrLength) {
@@ -5395,11 +5396,12 @@
       }
       // Assume cyclic values are equal.
       var stacked = stack.get(object);
-      if (stacked) {
+      if (stacked && stack.get(other)) {
         return stacked == other;
       }
       var result = true;
       stack.set(object, other);
+      stack.set(other, object);
 
       var skipCtor = isPartial;
       while (++index < objLength) {