Regex: Syntax pop on two linefeeds

I'm currently writing a Sublime syntax mode (YAML, for v3) for a language which has an unusual comment format.

Documentation comments:

start with the symbol # as the first character in a LOC, and
end with two newlines

A simple example is this:

# The following function returns
  the opposite of what you think it does.

code...

and a worst-case example:

#
  This is a comment,
this is still the same comment.
  This, too. These don't matter: # foobar ##

code...

My current approach is to use the stack.

Push:

- match: '#'
  scope: punctuation.definition.comment.mona
  push: doc_comment

Pop:

line_comment:
  - meta_scope: comment.line.mona
  - match: '\n\n'
    pop: true

That doesn't work though. I tried to fix this by using s, thinking that it would produce behavior like this, but it produces a Sublime error (invalid option for capture group).

How can I match this comment format correctly with S3 YAML?

Solution

Apparently I'm a bit thick today. The answer was obvious, to match on an empty line:

 - match: '^$'
   pop: true