srcset urls get replaced with "undefined" if they're absolute paths

[rbedemann]

Version

13.3.0

Reproduction link

https://github.com/rbedemann/vue-loader-bug

Steps to reproduce

Use absolute paths (p.ex. for images from static folder) instead of relative paths:

WORKING:
<img src="./logo.png" srcset="./logo.png 2x, ./logo.png 3x" />

NOT WORKING:
<img src="/static/images/logo.png" srcset="/static/images/logo.png 2x, /static/images/logo.png 3x" />

In reproduction link:
1.) check out repo
2.) run npm install
3.) run npm run dev

What is expected?

Paths to images in srcset attribute stay as they are.

What is actually happening?

Paths to images in srcset result in "undefined". the src attribute is still the same like before. I would expect same behaviour for srcset.