Closed issue by goleo108 on void-packages repository

https://github.com/void-linux/void-packages/issues/23639

Description:
@leahneukirchen here are examples how to fix it:
https://gitweb.gentoo.org/repo/gentoo.git/tree/dev-util/plan9port/plan9port-0_pre20200526.ebuild#n74
https://git.archlinux.org/svntogit/community.git/tree/trunk/PKGBUILD?h=packages/plan9port#n40
https://github.com/jrmarino/ravensource/blob/master/bucket_95/plan9port/specification#L59