Python Djapian：单字母查询加上通配符会导致错误

我一直在试验一个自动完成功能，它从用户键入的第一个字母开始搜索。目前，对于自动完成，我们在搜索词的末尾附加一个通配符*字符，以便我们可以匹配从该查询开始的词。但是，当使用只有一个字母加上通配符（例如s*的查询）的查询时，我会得到以下回溯错误：

Traceback:
File "/Users/myuser/.virtualenvs/ws/lib/python2.7/site-packages/django/core/handlers/base.py" in get_response
  115.                         response = callback(request, *callback_args, **callback_kwargs)
File "/Users/myuser/Development/site_project/myapp/myapp/ajax.py" in autocomplete_artist
  165.  for objArtistResult in objArtistResultSet:
File "/Users/myuser/.virtualenvs/ws/lib/python2.7/site-packages/djapian/resultset.py" in __iter__
  252.         self._fetch_results()
File "/Users/myuser/.virtualenvs/ws/lib/python2.7/site-packages/djapian/resultset.py" in _fetch_results
  221.             self._parse_results()
File "/Users/myuser/.virtualenvs/ws/lib/python2.7/site-packages/djapian/resultset.py" in _parse_results
  249.             self._do_prefetch()
File "/Users/myuser/.virtualenvs/ws/lib/python2.7/site-packages/djapian/resultset.py" in _do_prefetch
  201.                 hit.instance = instances[hit.pk]

Exception Type: KeyError at /ajax/autocomplete/artist/
Exception Value: 68651

当我尝试查找ID为异常值的记录时，找不到它，所以我不知道该值来自何处。还有其他人经历过吗