Updating to app-text/asciidoc-8.5.1 fixed the doc compilation. Please excuse not providing logs with details, I'm in a hurry.
Do you object fixing this myself?
(In reply to comment #1) > Do you object fixing this myself? Let me try and get to it in the next day days. If I still haven't fixed it by the end of the week, feel free to fix it for me.
Fixed in portage!