Build fails for carpentry: "incubator"

I am trying to set up a repository for a workshop based on a lesson in the incubator. When updating ``_config.yml`` with ``carpentry: "incubator"``, the workflows fail. The issue seems to be

```
Liquid Exception: Could not locate the included file 'incubator/intro.html' in any of ["/github/workspace/_includes", "/usr/local/bundle/gems/jekyll-theme-primer-0.6.0/_includes"]. Ensure it exists in one of those directories and is not a symlink as those are not allowed in safe mode. in index.md
```
If I change ``carpentry`` variable to something else, all the workflows succeed. Could you look into this? I will be happy to provide more info if required.