Fix searching with mixed CJK/non-CJK characters
Fix searching with mixed CJK/non-CJK characters

This fixes the following bug:
When a search query includes both CJK (like 'は') and non-CJK chars
(like '4'), then, on non-CJK indexes, the search is performed while
ignoring CJK chars, which brings many unwanted sentences (like
sentences just containing the character '4').

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