Expected Behaviour

Node to exit once webpack finished

Actual Behaviour

Node just hangs and doesn't exit.
Have tried node 10 and 12.
Both hang

Steps to Reproduce the Problem

1. clone this repository
2. yarn install
3. yarn build.
4. cd test/execution-tests/3.6.0_projectReferencesToBeBuilt
5. yarn install
6. ../../../node_modules/.bin/webpack-cli --config webpack.config.js

Location of a Minimal Repository that Demonstrates the Issue.

This repo