anchor.diff:              case length(hd(CandidateMap)) =:= length(hd(CurrentMap)) of
                   true ->
                       matching_renamings_same_vbuckets_count(KeepNodesSet, CurrentTags,
  -                                                           CandidateMap, CandidateTags);
  +                                                           CandidateMap, CandidateTags, Trivial);
                   false ->
                       []
               end
  
positive.code:                           case Compatible of
                                true ->
                                    matching_renamings_with_tags(NodesSet, {Map, Tags},
                                                                 {PastMap, PastTags});
                                false ->
                                    []
                            end
  
negative.code:                                 [{OldNodeA, NewNodeA}, {OldNodeB, NewNodeB}]) ++
                          rewrite_map(CandidateMap, CandidateTags, CurrentTags,
                                      [{OldNodeA, NewNodeB}, {OldNodeB, NewNodeA}]);
                  {_, false} ->
                      %% just try some random mapping just in case. It
                      %% will work nicely if NewNode-s are all being
                      %% added to cluster (and CurrentNode-s thus
  