What is the purpose of this pull request? (put an "X" next to item)

[X] Bug fix

Tell us about your environment

• ESLint Version: 6.1.0
• Node Version: 10.16.0
• npm Version: 6.9.0

What parser (default, Babel-ESLint, etc.) are you using?

default

Please show your full configuration:

module.exports = {
  parserOptions: {
    ecmaVersion: 2015,
  },
};

What did you do? Please include the actual source code causing the issue.

/*eslint no-self-assign: "error"*/

let a = [];

[...a] = [...a, 1]

console.log(a); // [ 1 ]

What did you expect to happen?

No errors as this is not a self assign.

What actually happened? Please include the actual, raw output from ESLint.

'a' is assigned to itself no-self-assign error

What changes did you make? (Give an overview)

Skip comparing a rest element if it isn't vs the last element.

Is there anything you'd like reviewers to focus on?