Fix tests on django 1.6

Author: kmmbvnr

tests/testapp/tests/test_lock_mixin.py

@@ -1,3 +1,6 @@
+import unittest
+
+import django
 from django.db import models
 from django.test import TestCase
 from django_fsm import FSMField, ConcurrentTransitionMixin, ConcurrentTransition, transition
@@ -87,6 +90,7 @@ def test_inheritance_crud_succeed(self):
         self.assertEqual('rejected', post.review_state)
         self.assertEqual('test_inheritance_crud_succeed2', post.text)
 
+    @unittest.skipIf(django.VERSION[:3] < (1, 8, 0), "Available on django 1.8+")
     def test_concurrent_modifications_after_refresh_db_succeed(self):  # bug 255
         post1 = LockedBlogPost.objects.create()
         post2 = LockedBlogPost.objects.get(pk=post1.pk)