misc: do not search for home URLs on requests to non-existant tenants (#61459)

src/authentic2/context_processors.py

@@ -73,6 +73,9 @@ def a2_processor(request):
 
 
 def home(request):
+    if not hasattr(request, 'session'):
+        # pure WSGIRequest, most probably happening for a request to a non-existant tenant.
+        return {}
     ctx = {}
     service = get_service(request)
     if service: