Unordered lists created with '+' and '-' not parsed

[jiahao]

Quoting the spec:

Unordered lists use asterisks, pluses, and hyphens — interchangably — as list markers:

but only the last of these is parsed as a list:

julia> Markdown.parse("""
+ List plus, item 1
+ List plus, item 2

- List minus, item 1
- List minus, item 2

* List times, item 1
* List times, item 2
""") |> println


Block(Content[Paragraph(Content[Plain("+ List plus, item 1 + List plus, item 2")]),Paragraph(Content[Plain("- List minus, item 1 - List minus, item 2")]),List(Content[Plain("List times, item 1"),Plain("List times, item 2")],true)])