When DOCS option is not definted, emulators/qemu-devel build fails because man pages are not built but still listed in the pkg-plist. BTW, I think the man pages should be built and installed regardless DOCS option is defined or not.
Yes. The MAN pages should be built irrespective to DOCS. Working on it.
A commit references this bug:
Date: Fri Oct 23 19:06:59 UTC 2020
New revision: 553134
emulators/qemu-devel: Update version 18.104.22.16800909=>22.214.171.12401010
- Fix plist when DOCS disabled 
PR: 250456 
Reported by: lwhsu