use char_group tokenizer to split on underscore.
use char_group tokenizer to split on underscore.

char_group tokenizer was added in ES 6.4.

LiquidPL/osu-web,notbakaneko/osu-web,ppy/osu-web,LiquidPL/osu-web,notbakaneko/osu-web,omkelderman/osu-web,LiquidPL/osu-web,nanaya/osu-web,notbakaneko/osu-web,ppy/osu-web,omkelderman/osu-web,ppy/osu-web,LiquidPL/osu-web,notbakaneko/osu-web,ppy/osu-web,nanaya/osu-web,ppy/osu-web,LiquidPL/osu-web,nanaya/osu-web,nanaya/osu-web,omkelderman/osu-web,omkelderman/osu-web,nanaya/osu-web,notbakaneko/osu-web