fix: CAS login infinite loop when user is disabled

apps/authentication/backends/cas/views.py

@@ -1,5 +1,7 @@
+from django.contrib.auth import logout as auth_logout
 from django.core.exceptions import PermissionDenied
 from django.http import HttpResponseRedirect
+from django.urls import reverse
 from django.utils.translation import gettext_lazy as _
 from django_cas_ng.views import LoginView
 
@@ -16,7 +18,11 @@ class CASLoginView(LoginView, FlashMessageMixin):
             resp = HttpResponseRedirect('/')
         error_message = getattr(request, 'error_message', '')
         if error_message:
-            response = self.get_failed_response('/', title=_('CAS Error'), msg=error_message)
+            auth_logout(request)
+            redirect_url = reverse('authentication:login') + '?admin=1'
+            response = self.get_failed_response(
+                redirect_url, title=_('CAS Error'), msg=error_message
+            )
             return response
         else:
             return resp