"arrow-parens": [true, "ban-single-arg-parens"] false alarms at (x): string => 'hey'

[zpdDG4gta8XKpMCd]

Bug Report

• "tslint": "5.0.0-dev.0",
• "typescript": "2.6.0-dev.20171005"
• node ./node_modules/tslint/bin/tslint --project ./scripts/src/tsconfig.json --config ./tslint-standard.json --format msbuild

TypeScript code being linted

// code snippet
const y = (x): string => 'hey';

with tslint.json configuration:

{
    "rules": {
        "arrow-parens": [ true, "ban-single-arg-parens" ]
    }
}

Actual behavior

Parentheses are prohibited around the parameter in this single parameter arrow function

Expected behavior

no error

[ajafff]

Fixed by #2265 released in 5.0.0