Setext headings in blockquotes

[hamvocke]

There seems to be a problem with Setext headings used within blockquotes.

Take this markdown input:

> Hello
> ----
> this is some other text

Running this on babelmark shows that most renderers will generate a blockquote that contains a heading and a paragraph. Markdig, however, creates a blockquote that contains a paragraph, a horizontal rule and another paragraph.

The CommonMark spec is not absolutely explicit about this case but generally states that --- characters should be treated as a Setext heading if they can be interpreted that way.

Is this something that should be fixed in Markdig to be closer to what other Markdown renderers are doing?

[xoofx]

It's definitely a bug, don't have time to look at this, but in case you have, PR welcome.