Files Tab "TypeError could not parse subscript as a tree path"

[Cas]

Have not investigated how to repeat yet but must have occurred while renaming torrents.

`Unhandled error in Deferred:
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/twisted/internet/tcp.py", line 460, in doRead
    return self.protocol.dataReceived(data)
  File "/home/calum/Documents/Coding/Deluge Work/deluge/deluge/ui/client.py", line 183, in dataReceived
    d.callback(request[2])
  File "/usr/lib/python2.7/dist-packages/twisted/internet/defer.py", line 361, in callback
    self._startRunCallbacks(result)
  File "/usr/lib/python2.7/dist-packages/twisted/internet/defer.py", line 455, in _startRunCallbacks
    self._runCallbacks()
--- <exception caught here> ---
  File "/usr/lib/python2.7/dist-packages/twisted/internet/defer.py", line 542, in _runCallbacks
    current.result = callback(current.result, *args, **kw)
  File "/home/calum/Documents/Coding/Deluge Work/deluge/deluge/ui/gtkui/files_tab.py", line 496, in _on_get_torrent_status
    self.update_folder_percentages()
  File "/home/calum/Documents/Coding/Deluge Work/deluge/deluge/ui/gtkui/files_tab.py", line 442, in update_folder_percentages
    if self.treestore[root][5] != -1:
exceptions.TypeError: could not parse subscript as a tree path`

[Cas]

Fixed 1.3-stable: ​c2b5d29c