This fixes:

  Traceback (most recent call last):
    ...
    File "neo/admin/handler.py", line 200, in answerLastTransaction
      app.maybeNotify(name)
    File "neo/admin/app.py", line 380, in maybeNotify
      self._notify(False)
    File "neo/admin/app.py", line 302, in _notify
      body += '', name, '    ' + backup.formatSummary(upstream)[1]
    File "neo/admin/app.py", line 74, in formatSummary
      tid = self.backup_tid if backup else self.ltid
  AttributeError: 'Backup' object has no attribute 'backup_tid'