diff --git a/src/pretix/base/models.py b/src/pretix/base/models.py
index 28e41eb3e8..20544ea0ba 100644
--- a/src/pretix/base/models.py
+++ b/src/pretix/base/models.py
@@ -44,7 +44,7 @@ class Versionable(BaseVersionable):
         if self.version_end_date:  # NOQA
             raise ValueError('This is a historical item and can not be cloned.')
 
-        if forced_version_date:
+        if forced_version_date:  # NOQA
             if not self.version_start_date <= forced_version_date <= get_utc_now():
                 raise ValueError('The clone date must be between the version start date and now.')
         else:
diff --git a/src/tests/base/test_models.py b/src/tests/base/test_models.py
index 7f7b1a3fac..8a5e474731 100644
--- a/src/tests/base/test_models.py
+++ b/src/tests/base/test_models.py
@@ -4,8 +4,8 @@ from django.test import TestCase
 from django.utils.timezone import now
 
 from pretix.base.models import (
-    CartPosition, Event, Item, ItemVariation, Order, OrderPosition, Organizer,
-    Property, PropertyValue, Question, Quota, User,
+    CartPosition, Event, Item, ItemCategory, ItemVariation, Order,
+    OrderPosition, Organizer, Property, PropertyValue, Question, Quota, User,
 )
 from pretix.base.services.orders import mark_order_paid
 from pretix.base.types import VariationDict
@@ -405,3 +405,30 @@ class OrderTestCase(BaseQuotaTestCase):
         assert self.order.can_modify_answers
         self.event.settings.set('last_order_modification_date', now() - timedelta(days=1))
         assert not self.order.can_modify_answers
+
+
+class ItemCategoryTest(TestCase):
+    """
+    This test case tests various methods around the category model.
+    """
+    @classmethod
+    def setUpTestData(cls):
+        o = Organizer.objects.create(name='Dummy', slug='dummy')
+        cls.event = Event.objects.create(
+            organizer=o, name='Dummy', slug='dummy',
+            date_from=now(),
+        )
+
+    def test_sorting(self):
+        c1 = ItemCategory.objects.create(event=self.event)
+        c2 = ItemCategory.objects.create(event=self.event)
+        assert c1 < c2
+        c1.position = 2
+        c2.position = 1
+        assert c2 < c1
+        assert not c1 < c2
+        assert c1 > c2
+        c1.position = 1
+        c2.position = 2
+        assert c1 < c2
+        assert c2 > c1
diff --git a/src/tests/control/test_orders.py b/src/tests/control/test_orders.py
index 74c7007fa3..41c25b3172 100644
--- a/src/tests/control/test_orders.py
+++ b/src/tests/control/test_orders.py
@@ -85,3 +85,16 @@ def test_order_transition_to_paid_success(client, env):
     })
     o = Order.objects.current.get(identity=env[2].identity)
     assert o.status == Order.STATUS_PAID
+
+
+@pytest.mark.django_db
+def test_order_transition_to_unpaid_success(client, env):
+    o = Order.objects.current.get(identity=env[2].identity)
+    o.status = Order.STATUS_PAID
+    o.save()
+    client.login(identifier='dummy@dummy.dummy', password='dummy')
+    client.post('/control/event/dummy/dummy/orders/FOO/transition', {
+        'status': 'n'
+    })
+    o = Order.objects.current.get(identity=env[2].identity)
+    assert o.status == Order.STATUS_PENDING
diff --git a/src/tests/presale/test_event.py b/src/tests/presale/test_event.py
index a3db225562..15da917573 100644
--- a/src/tests/presale/test_event.py
+++ b/src/tests/presale/test_event.py
@@ -237,6 +237,21 @@ class DeadlineTest(EventTestMixin, TestCase):
         self.assertIn('alert-danger', response.rendered_content)
         self.assertIn('is over', response.rendered_content)
 
+    def test_not_set(self):
+        self.event.presale_start = None
+        self.event.presale_end = None
+        self.event.save()
+        response = self.client.get(
+            '/%s/%s/' % (self.orga.slug, self.event.slug)
+        )
+        self.assertEqual(response.status_code, 200)
+        self.assertNotIn('alert-info', response.rendered_content)
+        self.assertIn('checkout-button-row', response.rendered_content)
+        response = self.client.post(
+            '/%s/%s/cart/add' % (self.orga.slug, self.event.slug)
+        )
+        self.assertNotEqual(response.status_code, 403)
+
     def test_in_time(self):
         self.event.presale_start = now() - datetime.timedelta(days=1)
         self.event.presale_end = now() + datetime.timedelta(days=1)