python - python ftputil の奇妙な動作

Question

次のようなコードがあります。

host = ftputil.FTPHost("ftp.example.com","anonymous","")

try:
    os.mkdir('./ftp.example.com')
except:
    traceback.print_exc()
else:
    sys.stderr.write('WTF?')

for root,dirs,files in host.walk('/Path/to/a/lot/of/census/data/files/',topdown=True,onerror=None):
    for filename in files:
        fullpath = os.path.join(root,filename)
        #print fullpath,host.lstat(fullpath)[6],int(host.lstat(fullpath)[8])
        try:
            host.download_if_newer(fullpath,'./ftp.example.com/'+filename,callback=None)
        except:
            traceback.print_exc()

しばらくすると、以下のような例外が端末画面のフラッディングを開始します。

*cmd* 'PWD'
*resp* '257 "/Path/to/a/lot/of/census/data/files/xx"'
*cmd* u'CWD /Path/to/a/lot/of/census/data/files/xx'
*resp* '257 "/Path/to/a/lot/of/census/data/files/xx"'
*cmd* u'TYPE I'
*resp* '250 Directory successfully changed.'
*cmd* 'PASV'
*resp* '200 Switching to Binary mode.'
Traceback (most recent call last):
  File "bdpublicdata.py", line 56, in <module>
    host.download_if_newer(fullpath,'./ftp.example.com/'+filename,callback=None)
  File "/usr/local/lib/python2.7/dist-packages/ftputil/host.py", line 521, in download_if_newer
    callback=callback)
  File "/usr/local/lib/python2.7/dist-packages/ftputil/file_transfer.py", line 176, in copy_file
    source_fobj = source_file.fobj()
  File "/usr/local/lib/python2.7/dist-packages/ftputil/file_transfer.py", line 91, in fobj
    return self._host.open(self.name, self.mode)
  File "/usr/local/lib/python2.7/dist-packages/ftputil/host.py", line 204, in open
    encoding=encoding, errors=errors, newline=newline)
  File "/usr/local/lib/python2.7/dist-packages/ftputil/file.py", line 194, in _open
    self._conn = self._session.transfercmd(command)
  File "/usr/local/lib/python2.7/dist-packages/ftputil/error.py", line 168, in __exit__
    raise FTPIOError(*exc_value.args)
FTPIOError: 200 Switching to Binary mode.
Debugging info: ftputil 3.1, Python 2.7.6 (linux2)
*cmd* 'PWD'
*resp* '227 Entering Passive Mode (126,218,41,23,59,181)'
Traceback (most recent call last):
  File "bdpublicdata.py", line 56, in <module>
    host.download_if_newer(fullpath,'./ftp.example.com/'+filename,callback=None)
  File "/usr/local/lib/python2.7/dist-packages/ftputil/host.py", line 521, in download_if_newer
    callback=callback)
  File "/usr/local/lib/python2.7/dist-packages/ftputil/file_transfer.py", line 176, in copy_file
    source_fobj = source_file.fobj()
  File "/usr/local/lib/python2.7/dist-packages/ftputil/file_transfer.py", line 91, in fobj
    return self._host.open(self.name, self.mode)
  File "/usr/local/lib/python2.7/dist-packages/ftputil/host.py", line 181, in open
    host = self._available_child()
  File "/usr/local/lib/python2.7/dist-packages/ftputil/host.py", line 159, in _available_child
    host._session.pwd()
  File "/usr/lib/python2.7/ftplib.py", line 587, in pwd
    return parse257(resp)
  File "/usr/lib/python2.7/ftplib.py", line 855, in parse257
    raise error_reply, resp
error_reply: 227 Entering Passive Mode (126,218,41,23,59,181)

また、ホストからディレクトリ ツリー全体を取得することはできません。

何かご意見は？