GIT_DIR unset in vc-git.el

[Emre Yolcu]

Hi,

In vc-git.el, the function vc-git--call unsets GIT_DIR before calling git.  
What is the reason for this? I am curious because I use a bare Git  
repository to manage my home directory, and this involves temporarily  
modifying GIT_DIR and GIT_WORK_TREE. More specifically, I use the function  
below, which keeps a modified environment for the duration of the  
recursive edit.

  (defun git-link-home ()
    (interactive)
    (let ((process-environment
           `(,(format "GIT_DIR=%s" (expand-file-name "~/.home.git/"))
             ,(format "GIT_WORK_TREE=%s" (expand-file-name "~/"))
             ,@process-environment)))
      (recursive-edit)))

This works fine for Magit, but not for VC. In particular, the Git branch  
information that is displayed in the mode line disappears because VC  
unsets GIT_DIR before calling git. Is there any harm in changing  
vc-git--call to not do that?

Best,
Emre