@turf/unkink-polygon v7.2.0 eliminates holes in polygons

The following Jest test calls unkink-polygon with a simple polygon consisting of a square with a square hole. This polygon has no kinks, so unkink should return the same feature back. Instead it returns two features, one being a polygon in the shape of the square but without any hole, and the other a square polygon in the shape of the hole.

import {polygon} from '@turf/helpers';
import unkinkPolygon from '@turf/unkink-polygon';

describe('@turf/unkink-polygon', () => {
  it('should work unkinking a square with a hole', () => {
    const feature = polygon([
      [[20,20],[0,20],[0,0],[20,0],[20,20]],
      [[15,15],[5,15],[5,5],[15,5],[15,15]]
    ]);
    const result = unkinkPolygon(feature);
    expect(result.features.length).toBe(1); // gets 2 features instead!
    expect(result.features[0]).toEqual(feature); // expect fails!
  });
});

Start at the @turf/unkink-polygon entry point and reproduce the supplied Jest case using a square with a square hole. Trace how the input feature is processed when it has no kinks. Done means the result contains one feature equal to the original polygon, including its hole.