Fix unit test.

see #799

modoboa/admin/tests/test_import_.py

@@ -3,6 +3,7 @@ from django.core.files.base import ContentFile
 from django.core.urlresolvers import reverse
 
 from modoboa.core.models import User
+from modoboa.lib import parameters
 from modoboa.lib.tests import ModoTestCase
 
 from .. import factories
@@ -15,6 +16,7 @@ class ImportTestCase(ModoTestCase):
     def setUpTestData(cls):
         """Create test data."""
         super(ImportTestCase, cls).setUpTestData()
+        parameters.save_admin("ENABLE_ADMIN_LIMITS", "no", app="limits")
         factories.populate_database()
 
     def test_domains_import(self):