Nope, the patch does not work for me.

I applied the patch in the Guix checkout, 
then

--8<---------------cut here---------------start------------->8---
$ ./pre-inst-env guix build man-db
...
/gnu/store/1w83i51wvap67kl7gdz51ly3pbbx29dv-man-db-2.8.3
$ /gnu/store/1w83i51wvap67kl7gdz51ly3pbbx29dv-man-db-2.8.3/bin/man nmcli-examples
--8<---------------cut here---------------end--------------->8---

Still truncated.

-- 
Pierre Neidhardt
https://ambrevar.xyz/