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: 
  
  do_last_checkpoint(#rep_state{seqs_in_progress = [],
      highest_seq_done = ?LOWEST_SEQ} = State) ->
      {stop, normal, cancel_timer(State)};
  do_last_checkpoint(#rep_state{seqs_in_progress = [],
      highest_seq_done = Seq} = State) ->
  
negative.code:     committed_seq,
      current_through_seq,
      seqs_in_progress = [],
      highest_seq_done = {0, ?LOWEST_SEQ},
      source_log,
      target_log,
      rep_starttime,
  