Accept HTTP 400 status code for Redfish fencing when host is already off

Some Redfish implementations (e.g., HPE iLo on ProLiant DL360 Gen11)
return HTTP 400 Bad Request when attempting to power off a host that is
already powered off, while others (e.g., Dell iDRAC) return HTTP 409
Conflict.

This commit extends the existing 409 handling to also accept 400 status
code, ensuring InstanceHA works correctly with HPE iLo and other vendors
that return 400 in this scenario.

The code now:
- Checks if the server is already powered off when receiving 400 or 409
- Verifies the actual power state via Redfish API
- Considers the fencing successful if the host is already OFF
- Provides improved logging that includes the status code in error cases

This fixes the issue where InstanceHA would fail to proceed with evacuation
when a host is already powered off on HPE ProLiant servers.

Author: antonioromito

templates/instanceha/bin/instanceha.py

@@ -686,17 +686,18 @@ def _host_fence(host, action):
                         return True
                 logging.error('Power off of %s timed out' % host)
                 return False
-            elif r.status_code == 409:
+            elif r.status_code in [400, 409]:
                 # Check if server is already powered off
+                # Some vendors (e.g., HPE iLo) return 400, others (e.g., Dell iDRAC) return 409
                 power_state = _redfish_get_power_state(url, user, passwd, timeout)
                 if power_state == 'OFF':
                     logging.info('Power off of %s ok (already off)' % host)
                     return True
                 else:
-                    logging.error('Could not power off %s (409 but not OFF: %s)' % (host, power_state))
+                    logging.error('Could not power off %s (%d but not OFF: %s)' % (host, r.status_code, power_state))
                     return False
             else:
-                logging.error('Could not power off %s' % host)
+                logging.error('Could not power off %s (status code: %d)' % (host, r.status_code))
                 return False
         else:
             r = _redfish_reset(url, user, passwd, timeout, "On")