Should tabbed code blocks allow an unclosed code block?

The commonmark spec allows an unclosed code block to extend to the end of the doc. I think we allowed this until #70, but didn't have a test for it?

Interesting. So what's the behavior now post-#70? Will it close the code block at the first line break? Or the next block component?

It won't match the block at all.

  ` ` `
  "will just be a regular code block"
  ` ` `
  ` ` `

  ` ` `
  tab 1
  ` ` `
  ` ` `
  tab 2
  ` ` `
  ` ` `
  Back to regular formatting

Updates, the second trailing-unclosed code block is now parsed as a code block, but not part of the tabs.