## Checklist

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## Issue

References listed at the same hierarchy level as a part are getting grouped within the last "Part" instead of appearing at the same level (in the Toc). 

![image](https://user-images.githubusercontent.com/8430564/172135451-7c86a07c-1146-4ad4-baeb-de4cd63308d7.png)


## Reprex

1. `quarto create-project mybook --type book`
2. Adjust `_quarto.yml` with content below
3. `quarto render --to pdf`

```
project:
  type: book

book:
  title: "mybook"
  author: "Jane Doe"
  date: "6/6/2022"
  chapters:
    - index.qmd
    - part: intro.qmd
      chapters:
      - summary.qmd
    - references.qmd

bibliography: references.bib

format:
  pdf:
    documentclass: book
```

## Metadata

```
quarto check

[✓] Checking Quarto installation......OK
      Version: 0.9.515
      Path: /Applications/quarto/bin

[✓] Checking basic markdown render....OK

[✓] Checking Python 3 installation....OK
      Version: 3.9.13
      Path: /opt/homebrew/opt/python@3.9/bin/python3.9
      Jupyter: (None)

      Jupyter is not available in this Python installation.
      Install with python3 -m pip install jupyter

[✓] Checking R installation...........OK
      Version: 4.2.0
      Path: /Library/Frameworks/R.framework/Resources
      LibPaths:
        - /Users/pjs/Library/R/arm64/4.2/library
        - /opt/R/4.2.0-arm64/Resources/site-library
        - /opt/R/4.2.0-arm64/Resources/library
      rmarkdown: 2.14

[✓] Checking Knitr engine render......OK
```
dragonstyle
2022-06-06T09:33:40Z
pat-s
verify-fixed
1.0
closed
PDF book: chapters are falsely grouped within a "part" (hierarchy wise)
https://github.com/quarto-dev/quarto-cli/issues/1075