anchor.diff:          source = Source,
           target = Target,
           history = OldHistory,
  -        start_seq = StartSeq,
  +        start_seq = {_, StartSeq},
           current_through_seq = {_Ts, NewSeq} = NewTsSeq,
           source_log = SourceLog,
           target_log = TargetLog,
  
positive.code:     [SourceLog, TargetLog] = find_replication_logs([Source, Target], Rep),
  
      {StartSeq0, History} = compare_replication_logs(SourceLog, TargetLog),
      StartSeq = get_value(since_seq, Options, StartSeq0),
      #doc{body={CheckpointHistory}} = SourceLog,
      State = #rep_state{
          rep_details = Rep,
  
negative.code: 
  
  do_last_checkpoint(#rep_state{seqs_in_progress = [],
      highest_seq_done = {_Ts, ?LOWEST_SEQ}} = State) ->
      {stop, normal, cancel_timer(State)};
  do_last_checkpoint(#rep_state{seqs_in_progress = [],
      highest_seq_done = Seq} = State) ->
  