Fix #2656 - Trailing slash on root.

backbone.js

@@ -1472,10 +1472,15 @@
     navigate: function(fragment, options) {
       if (!History.started) return false;
       if (!options || options === true) options = {trigger: !!options};
+
+      var trailing = fragment === '/';
       fragment = this.getFragment(fragment || '');
+
       if (this.fragment === fragment) return;
       this.fragment = fragment;
+
       var url = this.root + fragment;
+      if (!trailing && fragment === '') url = url.slice(0, -1);
 
       // If pushState is available, we use it to set the fragment as a real URL.
       if (this._hasPushState) {

test/router.js

@@ -656,4 +656,34 @@ $(document).ready(function() {
     Backbone.history.checkUrl();
   });
 
+  test('Trailing slash on root.', 1, function() {
+    Backbone.history.stop();
+    Backbone.history = _.extend(new Backbone.History, {
+      location: location,
+      history: {
+        pushState: function(state, title, url){
+          strictEqual(url, '/root');
+        }
+      }
+    });
+    location.replace('http://example.com/root/path');
+    Backbone.history.start({pushState: true, root: 'root'});
+    Backbone.history.navigate('');
+  });
+
+  test('Trailing slash on root.', 1, function() {
+    Backbone.history.stop();
+    Backbone.history = _.extend(new Backbone.History, {
+      location: location,
+      history: {
+        pushState: function(state, title, url){
+          strictEqual(url, '/root/');
+        }
+      }
+    });
+    location.replace('http://example.com/root/path');
+    Backbone.history.start({pushState: true, root: 'root'});
+    Backbone.history.navigate('/');
+  });
+
 });