anchor.diff:          false ->
               State2 = State#state{usable_vbuckets = NewUsableVBuckets},
               ?log_debug("Usable vbuckets:~n~p", [sets:to_list(State2#state.usable_vbuckets)]),
  -            change_vbucket_states(State2),
  +            update_vbucket_states(State2),
               {noreply, State2}
       end;
   
  
positive.code:                     %% uninteresting vbucket
                      ok;
                  false ->
                      change_vbucket_states(NewState)
              end,
              {reply, ok, NewState}
      end;
  
negative.code:             %% previous group for current value of design document can
              %% still be alive; thus using maybe_define_group
              maybe_define_group(DDocId, State),
              State;
          true ->
              ok
      end,
      update_vbucket_states(State),
      {noreply, State};
  
  handle_info(refresh_usable_vbuckets,
  