[tor-bugs] #18761 [Tor]: Make logging of rendezvous to private address quieter

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#18761: Make logging of rendezvous to private address quieter
------------------------+-------------------------------------------
     Reporter:  teor    |      Owner:
         Type:  defect  |     Status:  new
     Priority:  Medium  |  Milestone:  Tor: 0.2.8.x-final
    Component:  Tor     |    Version:  Tor: 0.2.8.2-alpha
     Severity:  Normal  |   Keywords:  must-fix-before-028-rc tor-hs
Actual Points:          |  Parent ID:
       Points:  small   |   Reviewer:
      Sponsor:          |
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 In #8976, we blocked rendezvous from hidden services to private addresses.

 But the warning is log_warn LD_REND, when arma wonders if it should be a
 protocol warning to avoid excessive logging on busy services:
 {{{
   log_warn(LD_REND, "%s on circ %u", err_msg,
            (unsigned)circuit->base_.n_circ_id);
 }}}

 There's also a whitespace issue we might as well fix while we're there:
 {{{
   if (err_msg_out) *err_msg_out = err_msg;
   else tor_free(err_msg);
 }}}

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/18761>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
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