title: RedirectToAction does not change the URL
body: <p>1.
  I have a home page (Home / Index). Here you select the language.
  Here the url is this: <code>"localhost:xxxx".</code></p>
  
  <p>2.
  After selecting the language, the following is a login page (Account / Index)
  Here the url is this: <code>"localhost:xxxx/Account/Index?language=en-US".</code></p>
  
  <p>3.
  When entering data (Username / Password) and click on the Logon button, redirects to User / Index but the url stays in Account/LogOn</p>
  
  <p>My Form:</p>
  
  <pre><code>&lt;% using (Html.BeginForm("LogOn", "Account")) { %&gt;
  &lt;div data-role="fieldcontain" class="ui-hide-label"&gt;
    &lt;label for="username"&gt;Username:&lt;/label&gt;
    &lt;%: Html.TextBoxFor(m =&gt; m.Username, new { placeholder = "Username" })%&gt;                      
  &lt;/div&gt;
  &lt;div data-role="fieldcontain" class="ui-hide-label"&gt;
    &lt;label for="password"&gt;Password:&lt;/label&gt;
    &lt;%: Html.PasswordFor(m =&gt; m.Password, new { placeholder = "Password" })%&gt;                 
  &lt;/div&gt;
  &lt;fieldset class="ui-grid-a"&gt;
    &lt;div class="ui-block-a"&gt;&lt;button type="reset" data-theme="d"&gt;Reset&lt;/button&gt;&lt;/div&gt;
    &lt;div class="ui-block-b"&gt;&lt;button type="submit" data-theme="b"&gt;Log On&lt;/button&gt;&lt;/div&gt;
  &lt;/fieldset&gt;             
  &lt;% } %&gt;
  </code></pre>
  
  <p>Account Controller:</p>
  
  <pre><code>[HandleError]
  public class AccountController : Controller
  {        
    public ActionResult Index(string language = "es-Es")
    {
      return View();
    }
  
    [HttpPost]
    public ActionResult LogOn(UserModel user)
    {
      FormsAuthentication.SetAuthCookie(user.Username, false);
      return RedirectToAction("Index", "User");
    }
  
    public ActionResult LogOff()
    {
      return View();
    }
  }
  </code></pre>
  
  <p>Global.asax:</p>
  
  <pre><code>public static void RegisterRoutes(RouteCollection routes)
  {
    routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
    routes.MapRoute(
                    "Default", // Route name
                    "{controller}/{action}/{id}", // URL with parameters
                   new { controller = "Home", action = "Index", id = UrlParameter.Optional } // Parameter defaults
                   );
  }
  </code></pre>
  
  <p>How to make the url is: localhost:xxxx/User/Index ?</p>