Comment 1 for bug 1814522

Thanks for the report and the excellent reproducer. It crashes due to infinite recursion in libxml2.
Luckily, it's easy to replace the call into libxml2 with custom code here – it's both more correct and faster.
Fix is here:
https://github.com/lxml/lxml/commit/201b712edf0478e6a94ace984c1e8435bf3bc3c3