mocha 4.0.0 hangs with mocha-mongoose

[amongouser]

Prerequisites

• Checked that your issue isn't already filed by cross referencing issues with the common mistake label
• Checked next-gen ES issues and syntax problems by using the same environment and/or transpiler configuration without Mocha to ensure it isn't just a feature that actually isn't supported in the environment in question or a bug in your code.
• 'Smoke tested' the code to be tested by running it outside the real test suite to get a better sense of whether the problem is in the code under test, your usage of Mocha, or Mocha itself
• Ensured that there is no discrepancy between the locally and globally installed versions of Mocha. You can find them with:
  node node_modules/.bin/mocha --version(Local) and mocha --version(Global). We recommend avoiding the use of globally installed Mocha.

Description

when running with:

    "mocha-mongoose": "^1.2.0",
    "mongoose": "^4.12.0"

It hangs:
https://travis-ci.org/amongouser/mocha-mongoose-hang/builds/283281361

works fine for mocha 3.x:
https://travis-ci.org/amongouser/mocha-mongoose-hang/builds/283280299

Steps to Reproduce

see this code: https://github.com/amongouser/mocha-mongoose-hang

Expected behavior: Runs ok like 3.x

Actual behavior: Hangs

Reproduces how often: 100%

Versions

see travis builds

Additional Information

mocha-mongoose issue: elliotf/mocha-mongoose#22

[boneskull]

see #3044; please read CHANGELOG before upgrading to a major release