## Description
Zola 0.17.0 fails to build/serve a site if it contains a `content/index.md` or `content/_index.md` file and a subproject, even though it is part of the recommended setup.

I don't expect a solution here, I just want to mention the workaround, and the upstream issue :
https://github.com/getzola/zola/issues/2101

## Error log
```
$ zola build
Building site...
Error: Failed to serve the site
Error: We can't have a page called `index.md` in the same folder as an index section in "/.../lafleur.presentmatter.one/content"
```

## Additional info
- Zola 0.16.0 is not affected. As a workaround, downgrade the package.


## Steps to reproduce
```
$ zola init test (press enter a few times)
$ cd test
$ echo --- >> content/_index.md
$ echo --- >> content/_index.md
$ mkdir content/test
$ echo --- >> content/test/index.md
$ echo --- >> content/test/index.md
$ zola serve
```