This commit fixes an issue introduced in the recently released Hugo 0.22.
This logic did not handle the case with root sections with non-section subfolders very well.
Fixes#3586
This enables both the variants below:
Current (first level only):
```
"blog": ":section/:title",
```
Nested (all levels):
```
"blog": ":sections/:title",
```
Should ideally been part of Hugo 0.22, but better late than never ...
Fixes#3580