cleanup

# Conflicts:
#	src/pretix/base/services/orders.py

src/pretix/helpers/database.py

@@ -21,6 +21,7 @@
 #
 import contextlib
 import logging
+
 from django.conf import settings
 from django.core.exceptions import FieldDoesNotExist, ImproperlyConfigured
 from django.db import connection, transaction
@@ -31,6 +32,7 @@ from django.utils.functional import lazy
 
 logger = logging.getLogger(__name__)
 
+
 class DummyRollbackException(Exception):
     pass