title: User.Identity.IsAuthenticated returns false after setting cookie and validating
body: <p>I am having a problem with MVC4 user authorization.</p>
  
  <p><code>System.Web.Security.Membership.ValidateUser</code> returns <code>true</code>.<br>
  Then it gets to <code>FormsAuthentication.SetAuthCookie</code> and I see a cookie in my browser.<br>
  Then <code>User.Identity.IsAuthenticated</code> still evaluates to <code>false</code> for some reason.<br>
  <code>User.Identity.IsAuthenticated</code> is still false after a redirect and stays <code>false</code>.</p>
  
  <pre><code>[AllowAnonymous]
  [HttpPost]
  public ActionResult Login(LoginModel model, string returnUrl)
  {
      if (ModelState.IsValid)
      {
          if (System.Web.Security.Membership.ValidateUser(model.UserName, model.Password))
          {
              FormsAuthentication.SetAuthCookie(model.UserName, model.RememberMe);
              if (Url.IsLocalUrl(returnUrl))
              {
                  return Redirect(returnUrl);
              }
              else
              {
                  return RedirectToAction("Index", "Home");
              }
          }
          else
          {
              ModelState.AddModelError("", "The user name or password provided is incorrect.");
          }
      }
  
      // If we got this far, something failed, redisplay form
      return View(model);
  }
  </code></pre>