Parse Error: Expected HTTP on localhost

Hello,
I'm facing some issue after updating from v6.0.0 to v7.2.0.
Trying to run wait-on by defining scripts in npm in my angular project:

```json
"scripts": {
"test:accessibility": "npm-run-all -p -r start check-accessibility",
"check-accessibility": "wait-on http://localhost:4600/ && hint --debug http://localhost:4600",
}
```

The server was starting, but nothing more was heppening. I used --verbose parameter and here is the errors I've got:
> making HTTP(S) head request to url:http://localhost:4600/ ...
> HTTP(S) error for http://localhost:4600/ Error: Parse Error: Expected HTTP/

As mentioned it was working well on v6.0.0. I also noticed that when I use 127.0.0.1 instead of localhost then it works well.