There is an updated pull request by zdtcd against master on the void-packages repository

https://github.com/zdtcd/void-packages git
https://github.com/void-linux/void-packages/pull/12666

register git-shell and change zsh completion
* zsh: use completion script from git itself
* git: register git-shell to /etc/shells


A patch file from https://github.com/void-linux/void-packages/pull/12666.patch is attached