Allow to render without context

Signed-off-by: Michal Čihař <michal@cihar.com>

weblate/trans/util.py

@@ -250,8 +250,10 @@ def get_project_description(project):
     )
 
 
-def render(request, template, context):
+def render(request, template, context=None):
     """Wrapper around Django render to extend context"""
+    if context is None:
+        context = {}
     if 'project' in context:
         context['description'] = get_project_description(context['project'])
     return django_render(request, template, context)