merge revision(s) 02b70256b5171d4b85ea7eeab836d3d7cfb3dbfc, 6b4f8945d600168bf530d21395da8293fbd5e8ba: [Backport #20909]
Check negative integer underflow Many of Oniguruma functions need valid encoding strings
merge revision(s) 02b70256b5171d4b85ea7eeab836d3d7cfb3dbfc, 6b4f8945d600168bf530d21395da8293fbd5e8ba: [Backport #20909]