[1.9.x] Fixed #26231 -- Used .get_username in admin login template.

{% if user.is_authenticated %}

<p class="errornote">

{% blocktrans with username=request.user.username trimmed %}

{% blocktrans with username=request.user.get_username trimmed %}

    You are authenticated as {{ username }}, but are not authorized to

    access this page. Would you like to login to a different account?

{% endblocktrans %}

  regressed in Django 1.9 (:ticket:`26253`).

* Fixed ``BoundField`` to reallow slices of subwidgets (:ticket:`26267`).

* Changed the admin's "permission denied" message in the login template to use

  ``get_username`` instead of ``username`` to support custom user models

  (:ticket:`26231`).