onFinish not invoked for explicit stack

[badeball]

Hi,

The following test seems to fail in (at least) 4.8.0, is it supposed to? Is it nearly identical to this test, with the only difference being that I create a new test harness.

var tap = require("tap");
var tape = require("tape").createHarness()

tap.test("on finish", {timeout: 1000}, function (tt) {
    tt.plan(1);
    tape.onFinish(function() {
        tt.pass('tape ended');
    });
    tape('dummy test', function(t) {
        t.end();
    });
});

[ljharb]

I've added a branch with a failing test: https://github.com/substack/tape/compare/harness_onfinish for anyone who wants to try to pick this up.