arbiters not required

diff --git a/stage2/models.py b/stage2/models.py
index 81625b9..cc1f1d5 100644 (file)
--- a/stage2/models.py
+++ b/stage2/models.py
@@ -63,7 +63,8 @@ class Assignment(models.Model):
     deadline = models.DateTimeField(_('deadline'))
     max_points = models.IntegerField(_('max points'))
     experts = models.ManyToManyField(User, verbose_name=_('experts'), related_name='stage2_assignments')
-    arbiters = models.ManyToManyField(User, verbose_name=_('arbiters'), related_name='stage2_arbitrated')
+    arbiters = models.ManyToManyField(
+        User, empty=True, verbose_name=_('arbiters'), related_name='stage2_arbitrated')
     file_descriptions = JSONField(_('file descriptions'))
 
     class Meta: