CLI Hooks ionic:serve:before is blocking ionic serve #2661

Description:

Defining an ionic:watch:before hook with a blocking script (e.g. an express server startup) will block ionic serve. Since the close resemblance to npm hook scripts it is expected to execute in a similar way; where prestart is non blocking for start.

Steps to Reproduce:

Clone repo: https://github.com/dnmd/cli-hooks

First

$ npm install

Non-blocking behaviour

$ npm start

This will executed both the prestart and start script.

Blocking behaviour

$ ionic serve

This will only execute the ionic:watch:before script.

Behaviour

When running ionic serve, the ionic:watch:before script is executed and opens a new terminal window, but doesn't continue the execution of ionic serve. When running npm start, the prestart script is executed and opens a new terminal window and does continue the execution of start.

My ionic info:
cli packages:

@ionic/cli-utils  : 1.8.1
ionic (Ionic CLI) : 3.8.1

global packages:

Cordova CLI : 7.0.1

local packages:

@ionic/app-scripts : 2.1.3
Cordova Platforms  : android 6.2.3
Ionic Framework    : ionic-angular 3.6.0

System:

Node : v6.6.0
npm  : 3.10.3
OS   : Windows 10