Subject of the issue
When a code block is indented with a TAB inside a list item, it's parsed wrong (code block contains triple quote symbol and language)
https://astexplorer.net/#/gist/6fe5a9f29e03ddf3169ff7ec0402f7ce/a9ff809ca89379f56e4832e658ebaf9e351cb9ff
Expected behaviour
The returned tree contains a code block with only code block contents.
Actual behaviour
The returned tree contains a code block with code block contents + wrapping quotes.
