Refs #56 -- Revert changes to recover from a problem

src/pretix/base/migrations/0008_auto_20150804_1357.py

@@ -0,0 +1,23 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import models, migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('pretixbase', '0007_auto_20150726_1430'),
+    ]
+
+    operations = [
+        migrations.AlterModelOptions(
+            name='order',
+            options={'verbose_name_plural': 'Orders', 'verbose_name': 'Order', 'ordering': ('-datetime',)},
+        ),
+        migrations.AlterField(
+            model_name='item',
+            name='default_price',
+            field=models.DecimalField(max_digits=7, decimal_places=2, verbose_name='Default price', null=True),
+        ),
+    ]

src/pretix/base/models.py

@@ -845,7 +845,7 @@ class Item(Versionable):
     )
     default_price = models.DecimalField(
         verbose_name=_("Default price"),
-        max_digits=7, decimal_places=2
+        max_digits=7, decimal_places=2, null=True
     )
     tax_rate = models.DecimalField(
         null=True, blank=True,