Fix test_authentication_with_invalid_tenant

Fixes bug 1099644

Change-Id: Ib58b4273054b8b57ef8770365b163f4bd42f93bc
diff --git a/tempest/tests/identity/admin/test_users.py b/tempest/tests/identity/admin/test_users.py
index 4c437ba..8a1cf71 100644
--- a/tempest/tests/identity/admin/test_users.py
+++ b/tempest/tests/identity/admin/test_users.py
@@ -182,10 +182,9 @@
                           self.data.test_tenant)
 
     @attr(type='negative')
-    @unittest.skip('Until Bug 988920 is fixed')
     def test_authentication_with_invalid_tenant(self):
         # User's token for an invalid tenant should not be authenticated
-        self.data.setup_one_user()
+        self.data.setup_test_user()
         self.assertRaises(exceptions.Unauthorized, self.token_client.auth,
                           self.data.test_user,
                           self.data.test_password,