Open remote conflicted file sometimes crashes

2015-03-25 16:52:26,884 15937 139706251187968 DEBUG    nxdrive.wui.dialog Load web file : /home/ataillefer/sources/nuxeo/addons/nuxeo-drive/nuxeo-drive-client/nxdrive/data/ui5/conflicts.html
2015-03-25 16:52:27,964 15937 139706251187968 DEBUG    nxdrive.wui.conflicts Should open this : Mode opératoire.docx (defaultFileSystemItemFactory#default#0d323df9-c29e-496c-9b57-ec53b1235b3d)
2015-03-25 16:52:27,965 15937 139706251187968 DEBUG    nxdrive.engine.engine Will try to open edit : 0d323df9-c29e-496c-9b57-ec53b1235b3d
2015-03-25 16:52:28,027 15937 139704850736896 DEBUG    nxdrive.engine.watcher.drive_edit Editing Mode opératoire.docx
Exception in thread Thread-12:
Traceback (most recent call last):
  File "/usr/lib/python2.7/threading.py", line 551, in __bootstrap_inner
    self.run()
  File "/usr/lib/python2.7/threading.py", line 504, in run
    self.__target(*self.__args, **self.__kwargs)
  File "/home/ataillefer/sources/nuxeo/addons/nuxeo-drive/nuxeo-drive-client/nxdrive/engine/engine.py", line 196, in run
    doc_ref, remote_name, user=self._remote_user)
  File "/home/ataillefer/sources/nuxeo/addons/nuxeo-drive/nuxeo-drive-client/nxdrive/engine/watcher/drive_edit.py", line 109, in edit
    tmp_file = self._download_content(engine, remote_client, info, file_path, url=url)
  File "/home/ataillefer/sources/nuxeo/addons/nuxeo-drive/nuxeo-drive-client/nxdrive/engine/watcher/drive_edit.py", line 75, in _download_content
    remote_client.get_blob(info.uid, file_out=file_out)
  File "/home/ataillefer/sources/nuxeo/addons/nuxeo-drive/nuxeo-drive-client/nxdrive/client/remote_document_client.py", line 389, in get_blob
    timeout=self.blob_timeout, file_out=file_out)
  File "/home/ataillefer/sources/nuxeo/addons/nuxeo-drive/nuxeo-drive-client/nxdrive/client/base_automation_client.py", line 350, in execute
    self.get_download_buffer())
TypeError: unsupported operand type(s) for +=: 'NoneType' and 'int'