Use request.get_host rather than hardcoded server name

 - Legacy-Id: 3876

Author: OleLaursen

ietf/templates/base.html

@@ -65,7 +65,7 @@
 <div id="ietf-login" class="noprint">{% if user.is_authenticated %}
 {{ user }}
 {% else %}
-<a href="https://datatracker.ietf.org/accounts/login/?next={{request.get_full_path|urlencode}}" rel="nofollow">Sign In</a>
+<a href="https://{{ request.get_host }}/accounts/login/?next={{request.get_full_path|urlencode}}" rel="nofollow">Sign In</a>
 {% endif %}</div>
 {% endif %}