Prior to this patch the ironic-python-agent service would only fallback
to use the old endpoints for /lookup and /heartbeat on a 404 error but,
since Ironic will check auth (if enabled) before it routes the requests
a 401 (Unauthorized) was returned.
Closes-Bug: #1612696
Change-Id: Idba5fed587e77aaa683d2c2b2126a520214712ce