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  /* The 'transports' list contains all the transports this proxy has
     launched.

     Before a managed_proxy_t reaches the PT_PROTO_COMPLETED phase,
     this smartlist contains a 'transport_t' for every transport it
     has launched.

     When the managed_proxy_t reaches the PT_PROTO_COMPLETED phase, it
     registers all its transports to the circuitbuild.c subsystem. At
     that point the 'transport_t's are owned by the circuitbuild.c
     subsystem.

     To avoid carrying dangling 'transport_t's in this smartlist,
     right before the managed_proxy_t reaches the PT_PROTO_COMPLETED
     phase we replace all 'transport_t's with strings of their
     transport names.

     So, tl;dr:
     When (conf_state != PT_PROTO_COMPLETED) this list carries
     (transport_t *).
     When (conf_state == PT_PROTO_COMPLETED) this list carries
     (char *).
   */