zh search with jiaba have a bug

Describe the bug
A clear and concise description of what the bug is.

To Reproduce
Steps to reproduce the behavior:

<Paste your command-line here which cause the problem>

$ git clone https://github.com/.../some_project
$ cd some_project
$ pip install -r requirements.txt
$ cd docs
$ make html SPHINXOPTS="-D language=de"
$ # open _build/html/index and see bla bla

Expected behavior
A clear and concise description of what you expected to happen.

Your project
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Screenshots
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Environment info

• OS: [e.g. Unix/Linux/Mac/Win/other with version]
• Python version: [e.g. 3.7.1]
• Sphinx version: [e.g. 1.8.2]
• Sphinx extensions: [e.g. sphinx.ext.autodoc, recommonmark]
• Extra tools: [e.g. Browser, tex or something else]

Additional context
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• [e.g. URL or Ticket]

The issue provides only the standard bug-report template and names no source file, test, project, environment, or reproducible command. Start by obtaining the missing reproduction details for Chinese search with jieba, then identify the relevant Sphinx search entry point and add a regression test; done means the reported search behavior is reproduced and corrected.