Links to resources in subfolders are not rewritten in index.html and print.html

[sam701]

Here is my directory structure

SUMMARY.md
dir1/
  content.md
  picture.png

There is a link to picture.png in content.md:

![my picture](./picture.png)

After mdbook build these files contain <img src="./picture.png" alt="my picture">

• book/index.html
• book/print.html
• book/dir1/content.html

This is correct for content.html but not for index.html and print.html. The image is not shown.

[MihaZupan]

Can confirm, images are broken when printing.