nokogiri supports the CSS selector parent:has(descendant) but does not support parent:has(>child). jQuery supports both, so it would be great if nokogiri would also support parent:has(>child).
Better jQuery selector support is on the roadmap for 2.0. See https://github.com/tenderlove/nokogiri/blob/master/ROADMAP.md for more details.
I'll note this issue in the roadmap.
For confused readers like myself: there's also a bug in :has() which confuses this further.