Use more sensible defaults for check-in lists in event series (#3147)

src/pretix/control/views/main.py

@@ -306,10 +306,11 @@ class EventWizard(SafeSessionWizardView):
                 event.set_active_plugins(settings.PRETIX_PLUGINS_DEFAULT.split(","),
                                          allow_restricted=settings.PRETIX_PLUGINS_DEFAULT.split(","))
                 event.save(update_fields=['plugins'])
-                event.checkin_lists.create(
-                    name=_('Default'),
-                    all_products=True
-                )
+                if not event.has_subevents:
+                    event.checkin_lists.create(
+                        name=_('Default'),
+                        all_products=True
+                    )
                 event.set_defaults()
 
             if basics_data['tax_rate']:

src/pretix/control/views/subevents.py

@@ -251,7 +251,9 @@ class SubEventEditorMixin(MetaDataEditorMixin):
                     'include_pending': False,
                 }
             ]
-            extra = 0
+
+            if not self.request.event.checkin_lists.filter(subevent__isnull=True).exists():
+                extra = 1
 
         formsetclass = inlineformset_factory(
             SubEvent, CheckinList,