From 2be771412b8aca39269b59778da259fd2fd16daf Mon Sep 17 00:00:00 2001
From: Irene Ros <irene@bocoup.com>
Date: Sat, 29 Oct 2011 12:27:46 -0400
Subject: [PATCH] Setting _unsetAttributes to false in unset rather than
 changedAttributes so that the unset attributes aren't lost on subsequent
 calls of changedAttributes. Added test to verify this behavior.

---
 backbone.js   | 2 +-
 test/model.js | 4 +++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/backbone.js b/backbone.js
index 190cb06a..a4fd089c 100644
--- a/backbone.js
+++ b/backbone.js
@@ -253,6 +253,7 @@
       if (!options.silent) {
         this.trigger('change:' + attr, this, void 0, options);
         this.change(options);
+        this._unsetAttributes = false;
       }
       return this;
     },
@@ -389,7 +390,6 @@
         changed[attr] = void 0;
       }
       
-      this._unsetAttributes = false;
       return changed;
     },
 
diff --git a/test/model.js b/test/model.js
index bfb499ea..76dc4b0b 100644
--- a/test/model.js
+++ b/test/model.js
@@ -175,7 +175,9 @@ $(document).ready(function() {
     model.unset('a', {silent: true});
     var changedAttributes = model.changedAttributes();
     ok('a' in changedAttributes, 'changedAttributes should contain unset properties');
-    equals(changedAttributes.a, undefined);
+
+    changedAttributes = model.changedAttributes();
+    ok('a' in changedAttributes, 'changedAttributes should contain unset properties when running changedAttributes again after an unset.');
   });
 
   test("Model: using a non-default id attribute.", function() {