comment on top doesn't have `parent`

[alexander-akait]

Input:

// this is a comment which results in an error!
.foo
  color: pink

Output (root):

Root {
  raws: { semicolon: undefined, before: '' },
  type: 'root',
  nodes: 
   [ Comment {
       raws: [Object],
       type: 'comment',
       text: 'this is a comment which results in an error!' },
     Rule {
       raws: [Object],
       type: 'rule',
       nodes: [Array],
       selector: '.foo',
       parent: [Circular],
       source: [Object],
       lastEach: 2,
       indexes: {} } ],
  source: 
   { start: { line: 1, column: 1 },
     end: { line: 3, column: 14 },
     input: 
      Input {
        css: '// this is a comment which results in an error!\n.foo\n  color: pink\n',
        file: '/home/evilebottnawi/IdeaProjects/stylelint/test.sass' } },
  lastEach: 2,
  indexes: {},
  rawCache: { semicolon: undefined } }

It is break stylelint in some places stylelint/stylelint#3244. It is bug or expected behaviour?

[Grawl]

fixed this with @at-root workaround
stylelint/stylelint#3244 (comment)