anchor.diff:  -define(BP_QUEUE,    5).
   -define(BP_STEPPED,  6).
   -define(BP_STEPPER,  7).
  +-define(EXC_SUBS,    8).
   
   %% userdevguide-begin gen_component:behaviour
   -ifdef(have_callback_support).
  
positive.code:                "** Source linetrace (enable in scalaris.hrl):~n ~.0p~n"
                 "** State:~n ~.0p~n"
                 "** Stacktrace:~n ~.0p~n",
      DbgVal = [Level, Reason,
                Msg,
                gc_mod(GCState),
                gc_hand(GCState),
                self(), catch pid_groups:group_and_name_of(self()),
                erlang:get(test_server_loc),
                {UState, GCState},
                Stacktrace],
      log_or_fail(DbgMsg, DbgVal, exception_throw).
  
  -spec log_or_fail(DbgMsg::string(), DbgVal::[term()],
                    Reason::unknown_message | exception_throw) -> ok.
  
negative.code:                           UState ->
                                DefaultHandler
                        end,
              T2State = case lists:keyfind(exception_subscription, 1, Options) of
                            {exception_subscription, Subs} ->
                                gc_set_exc_subs(T1State, Subs);
                            _ ->
                                T1State
                        end,
              {UState, gc_set_hand(T2State, Handler)}
          catch
              % If init throws up, send 'started' to the supervisor but exit.
              % The supervisor will try to restart the process as it is watching
  