Disable clean_step if config option is set to 0

Disabling erase_devices clean_step in agent_ilo driver doesn't work
even though the configuration option is updated to 0.

Change-Id: I72501793b9a0d384555bec2bbe2ddfdb2f1c2c2f
Closes-Bug:#1448103

ironic/drivers/modules/ilo/deploy.py

@@ -566,7 +566,7 @@ class IloVirtualMediaAgentDeploy(base.DeployInterface):
         :returns: A list of clean step dictionaries
         """
         steps = deploy_utils.agent_get_clean_steps(task)
-        if CONF.ilo.clean_priority_erase_devices:
+        if CONF.ilo.clean_priority_erase_devices is not None:
             for step in steps:
                 if (step.get('step') == 'erase_devices' and
                         step.get('interface') == 'deploy'):

ironic/tests/drivers/ilo/test_deploy.py

@@ -733,6 +733,22 @@ class IloVirtualMediaAgentDeployTestCase(db_base.DbTestCase):
             self.assertEqual(step[0].get('priority'),
                              CONF.ilo.clean_priority_erase_devices)
 
+    @mock.patch.object(deploy_utils, 'agent_get_clean_steps', autospec=True)
+    def test_get_clean_steps_erase_devices_disable(self, get_clean_step_mock):
+        self.config(clean_priority_erase_devices=0, group='ilo')
+        get_clean_step_mock.return_value = [{
+                'step': 'erase_devices',
+                'priority': 10,
+                'interface': 'deploy',
+                'reboot_requested': False
+                }]
+        with task_manager.acquire(self.context, self.node.uuid,
+                                  shared=False) as task:
+            step = task.driver.deploy.get_clean_steps(task)
+            get_clean_step_mock.assert_called_once_with(task)
+            self.assertEqual(step[0].get('priority'),
+                             CONF.ilo.clean_priority_erase_devices)
+
     @mock.patch.object(deploy_utils, 'agent_get_clean_steps', autospec=True)
     def test_get_clean_steps_without_conf_option(self, get_clean_step_mock):
         get_clean_step_mock.return_value = [{