Given the following (simplified) structure:

content
├── _index.md
├── orange.md
├── green
│   └── tea
│       └── index.md
├── purple
│   └── index.md
├── red
│   ├── flower
│   │   ├── _index.md
│   │   └── ...
└── yellow
    ├── _index.md
    └── ...

.Sections for /orange/ (and /purple/) contains:

Page(/green), 
Page(/yellow/_index.md), 
Page(/red)

This used to be [] in version 0.56 and below. Tested 0.57.x 0.58.x.