FIX: Naving to root URL was broken

app/assets/javascripts/discourse/lib/url.js.es6

@@ -221,6 +221,11 @@ const DiscourseURL = Ember.Object.extend({
     // TODO: Extract into rules we can inject into the URL handler
     if (this.navigatedToHome(oldPath, path, opts)) { return; }
 
+    // Navigating to empty string is the same as root
+    if (path === '') {
+      path = '/';
+    }
+
     return this.handleURL(path, opts);
   },