Nested lists are flattened inside alert blocks

[kaboc]

Example:

> [!NOTE]
> - Item1
>     - Item1-1
>     - Item1-2
>         - Item1-2-1
> - Item2
>     - Item2-1

GitHub	DartDoc

[sigurdm]

I believe this is an issue in package:markdown

Tried at https://dart-lang.github.io/tools/markdown/