The notification with the following header fails -
"Link: <https://websub.rocks/hub/100/sub/HdyJyGpboUHLlf3FON1k>;rel=self,<http://pubsubhubbub.appspot.com/>;rel=hub

When a space is added after the semicolons and commas, the test passes. AFAICT, the grammar in RFC5988 spec doesn't enforce spaces.

I see that the test uses IndieWeb\http_rels to extract the links which contains the following lines
$links = explode(', ', trim(substr($f, 6)));
and
$hrefandrel = explode('; ', $link);