anchor.diff:  
   handle_info({writer_checkpoint, SourceSeq}, #state{committed_seq=N} = State)
           when SourceSeq > N ->
  -    ?LOG_DEBUG("SourceSeq ~p N ~p", [SourceSeq, N]),
       MissingRevs = State#state.missing_revs,
       ok = gen_server:cast(MissingRevs, {update_committed_seq, SourceSeq}),
       couch_task_status:update("W Processed source update #~p", [SourceSeq]),
  
positive.code:     {ResultProps} = couch_rep_httpc:request(Req),
      true = proplists:get_value(<<"ok">>, ResultProps),
      proplists:get_value(<<"instance_start_time">>, ResultProps);
  ensure_full_commit(Db) ->
      {ok, NewDb} = couch_db:open(Db#db.name, []),
      UpdateSeq = couch_db:get_update_seq(Db),
      CommitSeq = couch_db:get_committed_update_seq(NewDb),
      InstanceStartTime = NewDb#db.instance_start_time,
      couch_db:close(NewDb),
      if UpdateSeq > CommitSeq ->
          ?LOG_DEBUG("replication needs a full commit: update ~p commit ~p",
              [UpdateSeq, CommitSeq]),
          {ok, NewTime} = couch_db:ensure_full_commit(Db),
          NewTime;
      true ->
          ?LOG_DEBUG("replication doesn't need a full commit", []),
          InstanceStartTime
      end.
  
  
negative.code:     end,
      {SourceStartTime, TargetStartTime}.
      
  ensure_full_commit(#http_db{} = Target) ->
      Req = Target#http_db{
          resource = "_ensure_full_commit",
          method = post,
          body = true
  