Unused var error missing when using es6 modules and arrow function (no-unused-vars)

[yangit]

export default (a, b)=> {
  console.log(a);
};

This code yields no errors.
Expected output is to get a no-unused-vars error for b variable.
Version is eslint 1.6.1
Settings are:

{
  "env": {
    "es6": true
  },
  "ecmaFeatures": {
    "modules": true
  },
  "rules": {
    "no-unused-vars": 2
  }
}

[eslintbot]

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1. The version of ESLint you are using (run eslint -v)
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4. What you expected to happen instead

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[mysticatea]

Thank you for reporting.

I can reproduce this.
I will try to fix...