Here's a link to the patch: https://reviews.freebsd.org/D29266
The patch seems OK. I have not tested if the two completions actually work, though.
A commit in branch main references this bug:
Author: Mateusz Piotrowski <0mp@FreeBSD.org>
AuthorDate: 2021-04-16 13:45:23 +0000
Commit: Mateusz Piotrowski <0mp@FreeBSD.org>
CommitDate: 2021-04-16 13:50:51 +0000
sysutils/vagrant: Enable Bash and Zsh completions
Approved by: firstname.lastname@example.org (maintainer)
Differential Revision: https://reviews.freebsd.org/D29266
sysutils/vagrant/Makefile | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)
Thanks! I've tested both bash and zsh at some point.