From 5310996d09a8b5772e0a0810a327575f02d3a42a Mon Sep 17 00:00:00 2001
From: Steve Mason <stevem@brandwatch.com>
Date: Thu, 11 Aug 2011 08:53:42 +0100
Subject: [PATCH 1/2] Test for unset attributes not being returned by
 changedAttributes

---
 test/model.js | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/test/model.js b/test/model.js
index 7ad0d71f..bfb499ea 100644
--- a/test/model.js
+++ b/test/model.js
@@ -170,6 +170,14 @@ $(document).ready(function() {
     equals(i, 2, 'Unset does not fire an event for missing attributes.');
   });
 
+  test("Model: unset and changedAttributes", function() {
+    var model = new Backbone.Model({a: 1});
+    model.unset('a', {silent: true});
+    var changedAttributes = model.changedAttributes();
+    ok('a' in changedAttributes, 'changedAttributes should contain unset properties');
+    equals(changedAttributes.a, undefined);
+  });
+
   test("Model: using a non-default id attribute.", function() {
     var MongoModel = Backbone.Model.extend({idAttribute : '_id'});
     var model = new MongoModel({id: 'eye-dee', _id: 25, title: 'Model'});

From 98877ff4b67259f45c74799c148bd5b30e13db87 Mon Sep 17 00:00:00 2001
From: Steve Mason <stevem@brandwatch.com>
Date: Thu, 11 Aug 2011 08:53:55 +0100
Subject: [PATCH 2/2] Fix for unset attributes not being returned by
 changedAttributes

---
 backbone.js | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/backbone.js b/backbone.js
index b2e49322..0a026452 100644
--- a/backbone.js
+++ b/backbone.js
@@ -374,6 +374,12 @@
           changed[attr] = now[attr];
         }
       }
+      for (attr in old){
+        if (!(attr in now)){
+          changed = changed || {};
+          changed[attr] = void 0;
+        }
+      }
       return changed;
     },