in jekyll/plugins/markdown_converter.rb [265:273]
def initialize(source, options)
super
{:codeblock_fenced_gfm => :codeblock_fenced_gfm_indented}.each do |current, replacement|
i = @block_parsers.index(current)
@block_parsers.delete(current)
@block_parsers.insert(i, replacement)
end
end