Fix rendering of registration email

html/registration/activation_email.txt

-{% load url from future %}{% load i18n %}{% load weblate %}{% filter wordwrap:72 %}{% blocktrans %}Hi,
+{% load url from future %}{% load i18n %}{% load weblate %}{% filter wordwrap:72 %}{% blocktrans with site|site_title as site_title %}Hi,
 
 This is an automatic email to help you complete your registration
-with {% site_title %}.
+with {{ site_title }}.
 
 Please open the following link in your web browser. If the link
 is split over several lines, you may need to copy it in the
@@ -9,10 +9,10 @@ address bar.{% endblocktrans %}
 
 http://{{ site.domain }}{% url 'registration.views.activate' activation_key=activation_key %}
 
-{% blocktrans %}
+{% blocktrans with site|site_title as site_title %}
 If there is a problem with your registration, please reply to
 this email.
 
 Best regards,
-{% site_title %}
+{{ site_title }}
 {% endblocktrans %}{% endfilter%}

html/registration/activation_email_subject.txt

-{% load i18n %}{% load weblate %}{% blocktrans %}Your registration on {% site_title %}{% endblocktrans %}
+{% load i18n %}{% load weblate %}{% blocktrans with site|site_title as site_title %}Your registration on {{ site_title }}{% endblocktrans %}

trans/templatetags/weblate.py

@@ -31,6 +31,7 @@ def fmttranslation(value):
     return mark_safe(value)
 
 
-@register.simple_tag
-def site_title():
+@register.filter
+@stringfilter
+def site_title(value):
     return settings.SITE_TITLE