Investigation: can't upgrade Acorn to 7.x

[sapegin]

I'm trying to upgrade Acorn from 6.30 to 7.0.0 (or 7.1.0) and it doesn't work:

SyntaxError: Unexpected token (1:6)
1 : <React.Fragment><Button>Push Me</Button></React.Fragment>;
          ^

SyntaxError: Unexpected token (3:15)
1 : import Placeholder from '../Placeholder'
2 : ;<Button>
3 :   <Placeholder />
                   ^

I don't see any migration guide or changes that may break JSX parsing. Any hints would be great here.

[malyzeli]

Probably related to #1321

[sapegin]

@malyzeli I think you're right, closing this one as duplicate.