Fix error 500 on CAS logout page if no HTTP Referer is provided (#43221)

License: MIT

src/authentic2_idp_cas/views.py

@@ -464,7 +464,7 @@ class LogoutView(View):
     http_method_names = ['get']
 
     def get(self, request):
-        referrer = request.META['HTTP_REFERER']
+        referrer = request.headers.get('Referer')
         next_url = request.GET.get('service') or make_url('auth_homepage')
         if referrer:
             model = Service.objects.for_service(referrer)