“主题设置”无法保存，点保存就会报这个错误

Traceback (most recent call last):
File "/base/python_runtime/python_lib/versions/1/google/appengine/ext/webapp/__init__.py", line 513, in __call__
handler.post(*groups)
File "/base/data/home/apps/gaoshier/1.346212161153461745/backstage.py", line 1619, in post
template_values['page_title'] = site.title + u' › ' + l10n.backstage + u' › ' + l10n.topic_settings
UnicodeDecodeError: 'ascii' codec can't decode byte 0xe5 in position 0: ordinal not in range(128)

另：主题设置的是节点吗？如果不是，那节点在哪儿设置？