BUG: "git var GIT_SHELL_PATH" is broken on Windows

Running "git var GIT_SHELL_PATH" on Windows prints "/bin/sh" which is not very helpful when the path to the shell is actually "C:\Users\gitlab_runner\scoop\apps\mingit-busybox\2.45.2\mingw64\bin\ash.exe"

Support for GIT_SHELL_PATH was added to "git var" in 1e65721227 (var: add support for listing the shell, 2023-06-27) with the aim of making it possible for external programs to learn the location of the shell used to run the command returned by "git var GIT_EDITOR". As the commit message notes this is especially helpful on Windows where the shell isn't necessarily in $PATH. Unfortunately the implementation simply prints SHELL_PATH which is unused on Windows. As 776297548e (Do not use SHELL_PATH from build system in prepare_shell_cmd on Windows, 2012-04-17) explains the location of the shell depends on git's installation prefix. For the git-for-windows builds it looks like the shell is always in "$GIT_EXEC_PATH/../../bin/" but I'm not sure if that is universally true.

It is possible to work around the bug by doing

     git -c 'alias.run-editor=!$(git var GIT_EDITOR)' run-editor

but it would be good to fix "git var GIT_SHELL_PATH" or at least document that it is broken on Windows

Best Wishes

Phillip