urpose that the circuit is intended for
:var stem.HiddenServiceState hs_state: status if this is a hidden service circuit
:var str rend_query: circuit's rendezvous-point if this is hidden service related
:var datetime created: time when the circuit was created or cannibalized
:var stem.CircPurpose old_purpose: prior purpose for the circuit
:var stem.HiddenServiceState old_hs_state: prior status as a hidden service circuit
)