Fix import of supervision substitutions

aleksis/apps/untis/util/mysql/importers/events.py

@@ -5,7 +5,7 @@ from django.utils.translation import gettext as _
 from reversion import create_revision, set_comment
 from tqdm import tqdm
 
-from aleksis.apps.chronos.models import LessonEvent
+from aleksis.apps.chronos.models import LessonEvent, SupervisionEvent
 from aleksis.apps.lesrooster.models import ValidityRange
 
 from .... import models as mysql_models
@@ -140,7 +140,7 @@ def import_events(
         extended_data__event_untis__isnull=False,
         datetime_start__date__lte=validity_range.date_end,
         datetime_end__date__gte=validity_range.date_start,
-    ):
+    ).not_instance_of(SupervisionEvent):
         if e.extended_data["event_untis"] not in existing_events:
             logger.info(f"Event {e.id} deleted")
             with create_revision():