How to have a post Thumbnail from an image in a post bundle

[Yaxit]

I have the following file structure

blog/
├─ post1/
│ ├─ index.md
│ ├─ cover.jpg

And I'm trying to use cover.jpg as thumbnail of the post. If I use the "image" parameter, the image is then referenced as absolute path, e.g.: once build the website will try to refer to /cover.jpg (from root) and miss.

How can this be achieved? I also had saw issue #44 but maybe this relates to images in the static folder?