{% if user.is_authenticated %}
<span class="user_name">{{ user.username }}</span> | 
<a href='{% url django.contrib.auth.views.logout %}?next={{request.get_full_path}}'>Wyloguj</a>
{% else %}
{% url django.contrib.auth.views.login as login_url %}
{% ifnotequal login_url request.path %}
    <a href='{% url django.contrib.auth.views.login %}?next={{request.get_full_path}}'>Logowanie</a>
{% endifnotequal %}

{% endif %}