Merge "add HEAD sentinel file that contains migration revision"

diff --cc neutron/tests/unit/test_db_migration.py
index 83c2ede4f953964ec01f47f4915bc9fcbed55e9e,be3265bea2619a96b48192ab3a71e4f521029c66..9147a6701251eb9f82a50e1188f6a4c668f0bfc1
--- 1/neutron/tests/unit/test_db_migration.py
--- 2/neutron/tests/unit/test_db_migration.py
+++ b/neutron/tests/unit/test_db_migration.py
@@@ -40,7 -40,10 +40,9 @@@ class TestCli(base.BaseTestCase)
          super(TestCli, self).setUp()
          self.do_alembic_cmd_p = mock.patch.object(cli, 'do_alembic_command')
          self.do_alembic_cmd = self.do_alembic_cmd_p.start()
+         self.mock_alembic_err = mock.patch('alembic.util.err').start()
+         self.mock_alembic_err.side_effect = SystemExit
          self.addCleanup(self.do_alembic_cmd_p.stop)
 -        self.addCleanup(cli.CONF.reset)
  
      def _main_test_helper(self, argv, func_name, exp_args=(), exp_kwargs={}):
          with mock.patch.object(sys, 'argv', argv):