looking at the source, python is only used for "make dist" and maybe for pypi distribution. the Arch package does not use python: https://git.archlinux.org/svntogit/community.git/tree/trunk/PKGBUILD?h=packages/knot. I tested the package removing USES = python and it appears to compile and operate correctly.
python-sphinx is used when building docs, so can be conditional.
I'd like to merge this report with PR 242665 to keep the number of open PR's limited.
(In reply to Leo Vandewoestijne from comment #1)
It's preferable and less confusing to separate bugfixes (this bug) from updates (bug 242665) so that the former (bugfixes) can be merged to the quarterly branch, whereas version updates, unless they are bugfix only releases, generally are not.
This PR can be closed;
it's addressed in PR 242665 - see patch #210967 or later.
^Triage: Correct resolution, resolved by bug 242665