Errors from zsh in git function from `/usr/share/zsh/site-functions/_git` when using tab completion in a git directory - if bash is the login shell

Please confirm there isn't an open report for this issue

• I have searched through bug reports

Summary

On a system where the login shell is bash, if I switch to zsh, completion in a git directory causes errors. Note that we have sometimes instructed users to use bash as the login shell to workaround problems at login.

Whenever I'm in a 'git' repo directory, run a command, and use Tab to complete, I get the following error (the command is git switch and everything after that is the error text):

$ git switch usingWelcome!          
_git:.:48: no such file or directory: 
/usr/share/zsh/site-functions/git-completion.bash
__git_zsh_bash_func:8: command not found: __git_aliased_command
__git_zsh_bash_func:8: command not found: __git_aliased_command
__git_zsh_bash_func:8: command not found: __git_aliased_command

This makes tab completion in zsh pretty unusable unless the login shell is zsh

Steps to reproduce

1. In terminal, be in a git directory like $HOME/solus-packages/packages
2. Run a partial command like git switch and press Tab

Expected result

Tab completion is successful

Actual result

Tab completion works, but there is the error output

Environment

• Is system up to date?

Repo

Unstable

Desktop Environment

Plasma

System details

Operating System: Solus 4.7
KDE Plasma Version: 6.5.2
KDE Frameworks Version: 6.19.0
Qt Version: 6.9.3
Kernel Version: 6.16.12-323.current (64-bit)
Graphics Platform: Wayland
Processors: 16 × 11th Gen Intel® Core™ i7-11800H @ 2.30GHz
Memory: 64 GiB of RAM (62.5 GiB usable)
Graphics Processor 1: Intel® UHD Graphics
Graphics Processor 2: NVIDIA GeForce RTX 3060 Laptop GPU

eopkg info zsh      
Installed package:
Name                : zsh, version: 5.9, release: 36

Other comments

The function is in /usr/share/zsh/site-functions/_git
According to the pspec_x86_64.xml file we do install the bash completions here
/usr/share/zsh/functions/_bash_completions

The file the function is looking for is here
/usr/share/zsh/site-functions/git-completion.bash

This happens on only one of the two laptops I have running unstable. They both have zsh installed but the error occurs on the system where bash is the login shell and I switch to zsh in the terminal. On the system where zsh is the login shell, completions work as expected.

Start with /usr/share/zsh/site-functions/_git and compare its referenced git-completion.bash path with /usr/share/zsh/functions/_bash_completions and the package spec mentioned in the report. Reproduce after switching from a bash login shell to zsh in a Git directory, then verify that tab completion produces no error output.