问带有流氓的Kramdown没有生成<pre>包装器

EN

> input = <<-HEREDOC
* # Header 1
* ## Header 2
*
* ```
* def hello
*   puts "hello world"
* end
* ```
* HEREDOC
=> "# Header 1\n## Header 2\n\n```\ndef hello\n  puts \"hello world\"\nend\n```\n"
> Kramdown::Document.new(input, input: "GFM", syntax_highlighter: "rouge").to_html
=> "<h1 id=\"header-1\">Header 1</h1>\n<h2 id=\"header-2\">Header 2</h2>\n\n<div class=\"highlighter-rouge\">def hello\n  puts \"hello world\"\nend\n</div>\n"

> Kramdown::Document.new(input, input: "GFM").to_html
=> "<h1 id=\"header-1\">Header 1</h1>\n<h2 id=\"header-2\">Header 2</h2>\n\n<pre><code>def hello\n  puts \"hello world\"\nend\n</code></pre>\n"