Merge pull request #3875 from Flamefork/3871-set-parse-undefined

Fixed Collection#set regression when parse returns falsy value

backbone.js

@@ -824,7 +824,7 @@
       if (options.parse && !this._isModel(models)) models = this.parse(models, options);
 
       var singular = !_.isArray(models);
-      models = singular ? [models] : models.slice();
+      models = singular ? (models ? [models] : []) : models.slice();
 
       var at = options.at;
       if (at != null) at = +at;

test/collection.js

@@ -1817,4 +1817,12 @@
     model.trigger('change');
   });
 
+  QUnit.test('#3871 - falsy parse result creates empty collection', function(assert) {
+    var collection = new (Backbone.Collection.extend({
+      parse: function (data, options) {}
+    }));
+    collection.set('', { parse: true });
+    assert.equal(collection.length, 0);
+  });
+
 })();