Verify behavior when package has dependency on itself

[bmish]

Double-check that the behavior is correct.

{
  "name": "foo",
  "dependencies": {
    "foo": "file:./" 
  }
}

Example, an ESLint plugin that has a dependency on itself so that it can run its own lint rules on itself:

• https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/99bf9b7b5f75d5b7aee056aee62309b5f09e5879/package.json#L52

https://yarnpkg.com/features/protocols