anchor.diff:      catch
           throw:{zerf,no_common} ->
               FirstEpoch_p = case get(epochs) of
  -                               [0]                                -> true;
  -                               [?SET_CHAIN_MEMBERS_EPOCH_SKIP, 0] -> true;
  -                               _                                  -> false
  +                               [0]    -> true;
  +                               [_, 0] -> true;
  +                               _      -> false
                              end,
               if FirstEpoch_p ->
                       %% Epoch 0 special case: make the "all" projection.
  
positive.code: 
  react_to_env_B10(Retries, P_newprop, P_latest, LatestUnanimousP,
                   Rank_newprop, Rank_latest,
                   #ch_mgr{name=MyName, flap_limit=FlapLimit}=S)->
      ?REACT(b10),
  
      {_P_newprop_flap_time, P_newprop_flap_count} = get_flap_count(P_newprop),
      UnanimousLatestInnerNotRelevant_p =
          case inner_projection_exists(P_latest) of
              true when P_latest#projection_v1.author_server /= MyName ->
                  #projection_v1{down=Down_inner} = inner_projection_or_self(
                                                      P_latest),
                  case lists:member(MyName, Down_inner) of
                      true ->
                          %% Some foreign author's inner projection thinks that
  
negative.code:                     P = make_all_projection(MyName, AllMembers, OldWitness_list,
                                              MembersDict),
                      machi_projection:update_checksum(
                        P#projection_v1{epoch_number=OldEpochNum,dbg2=[zerf_all]});
                 true ->
                      %% Make it appear like nobody is up now: we'll have to
                      %% wait until the Up list changes so that
                      %% zerf_find_last_common() can confirm a common stable
                      %% last stable epoch.
  
                      P = make_none_projection(MyName, AllMembers,OldWitness_list,
                                               MembersDict),
                      machi_projection:update_checksum(
                        P#projection_v1{epoch_number=OldEpochNum,dbg2=[zerf_none]})
              end;
          _X:_Y ->
              throw({zerf, {damn_exception, Up, _X, _Y, erlang:get_stacktrace()}})
  