GoogleAppEngineについて

GoogleAppEngineのローダーで日本語のCSVデータがアップロード出来ない問題について。
下記のようなエラーが発生します。

[home]>appcfg.py upload_data -
-config_file=src/state_loader.py --filename=ken_all.csv --kind=State 
--url=[site_url]/remote_api [GoogleAppEngine]
C:\Program Files\Google\google_appengine\appcfg.py:41: DeprecationWarning: the s
ha module is deprecated; use the hashlib module instead
  os.path.join(DIR_PATH, 'lib', 'antlr3'),
Application: oesoesoes; version: 1.
Uploading data records.
[INFO    ] Logging to bulkloader-log-20100110.103751
[INFO    ] Throttling transfers:
[INFO    ] Bandwidth: 250000 bytes/second
[INFO    ] HTTP connections: 8/second
[INFO    ] Entities inserted/fetched/modified: 20/second
[INFO    ] Opening database: bulkloader-progress-20100110.103751.sql3
[INFO    ] Connecting to oesoesoes.appspot.com/remote_api
[INFO    ] Starting import; maximum 10 entities per post
[ERROR   ] [WorkerThread-0] WorkerThread:
Traceback (most recent call last):
  File "C:\Program Files\Google\google_appengine\google\appengine\tools\adaptive
_thread_pool.py", line 150, in WorkOnItems
    status, instruction = item.PerformWork(self.__thread_pool)
  File "C:\Program Files\Google\google_appengine\google\appengine\tools\bulkload
er.py", line 671, in PerformWork
    transfer_time = self._TransferItem(thread_pool)
  File "C:\Program Files\Google\google_appengine\google\appengine\tools\bulkload
er.py", line 828, in _TransferItem
    self.request_manager.PostEntities(self.content)
  File "C:\Program Files\Google\google_appengine\google\appengine\tools\bulkload
er.py", line 1252, in PostEntities
    datastore.Put(entities)
  File "C:\Program Files\Google\google_appengine\google\appengine\api\datastore.
py", line 195, in Put
    req.entity_list().extend([e._ToPb() for e in entities])
  File "C:\Program Files\Google\google_appengine\google\appengine\api\datastore.
py", line 576, in _ToPb
    properties = datastore_types.ToPropertyPb(name, values)
  File "C:\Program Files\Google\google_appengine\google\appengine\api\datastore_
types.py", line 1577, in ToPropertyPb
    pbvalue = pack_prop(name, v, pb.mutable_value())
  File "C:\Program Files\Google\google_appengine\google\appengine\api\datastore_
types.py", line 1409, in PackString
    pbvalue.set_stringvalue(value.encode('utf-8'))
UnicodeDecodeError: 'ascii' codec can't decode byte 0xe3 in position 0: ordinal
not in range(128)
[INFO    ] Backing off due to errors: 1.0 seconds
[INFO    ] An error occurred. Shutting down...
[ERROR   ] Error in WorkerThread-0: 'ascii' codec can't decode byte 0xe3 in posi
tion 0: ordinal not in range(128)

[INFO    ] 1 entites total, 0 previously transferred
[INFO    ] 0 entities (706 bytes) transferred in 1.6 seconds
[INFO    ] Some entities not successfully transferred
end

「bulkloader.py」が問題かとおもいきや、その先で実行されている「datastore_types.py」が問題の様子。
問題調査のため下記の通り修正してみると、動いてしまった。。。

1409行目
pbvalue.set_stringvalue(value.encode('utf-8'))
↓
1409行目
pbvalue.set_stringvalue(value)

ん！？
何故、明示的に変換処理している所で「UnicodeDecodeError」って言われてるの？
あぁ、もちろんファイルはUTF-8にしてるけどね。
調査はしたいけど、現在アップローダーで登録中なのでまた次回に。