Make tests passed on Django 1.5+

tests/manage.py

 #!/usr/bin/env python
-from django.core.management import execute_manager
-try:
-    import settings # Assumed to be in the same directory.
-except ImportError:
-    import sys
-    sys.stderr.write("Error: Can't find the file 'settings.py' in the directory containing %r. It appears you've customized things.\nYou'll have to run django-admin.py, passing it your settings module.\n(If the file settings.py does indeed exist, it's causing an ImportError somehow.)\n" % __file__)
-    sys.exit(1)
+import os
+import sys
 
 if __name__ == "__main__":
-    execute_manager(settings)
+    os.environ.setdefault("DJANGO_SETTINGS_MODULE", "tests.settings")
+
+    from django.core.management import execute_from_command_line
+
+    execute_from_command_line(sys.argv)

tests/settings.py

@@ -22,3 +22,5 @@ CACHES = {
 }
 
 ROOT_URLCONF = 'tests.urls'
+
+SECRET_KEY = 'blabla'