anchor.diff:  %% ===================================================================
   %% gen_server callback stubs
   
  -terminate(normal, _S) ->
  +terminate(Reason, _S)
  +  when Reason =:= normal; Reason =:= done ->
       ok;
   terminate(Reason, #state{phase = Phase} = _S) ->
       error_logger:warning_report({"GC: dying", Reason, Phase}).
  
positive.code:             % We haven't made progress. Stop GC.
              error_logger:error_report({"GC: progress timeout in phase",
                                         S#state.phase}),
              {stop, normal, S}
      end;
  handle_info(check_progress, S) ->
      % We don't need this timer in the RR phases.
  
negative.code:     % Unexpected exit of RR process; exit.
      error_logger:error_report({"GC: unexpected exit of replicator",
                                 Reason, Phase}),
      {stop, replicator_error, S};
  
  handle_info({'EXIT', Pid, Reason}, #state{phase = Phase} = S) ->
      case find_node(S#state.gc_peers, Pid) of
  