git-config: replaces ~/.gitconfig symlink with real file

Since the number of dot-files and dot-directories that I have in my
home directory these days is somewhat overwhelming, I like to keep
those I directly edit all together in an ~/etc directory so I can
easily back them up and/or copy them in bulk to new accounts.  So,
several of my home dot-files are just symlinks to something in ~/etc,
including ~/.gitconfig.

However, when I tried running 'git-config --global color.diff auto'
today, it removed my symlink and replaced it with a real file.  This
left me briefly a bit confused when the changes I had made didn't show
up in ~/etc/gitconfig, but git-config reported them anyway.

If I were to fix this, I'd be tempted to use realpath(3) to follow the
symlink, but I don't think it's very reliably available
cross-platform.  Certainly, it isn't used anywhere in the current git
code.  Can anyone suggest a more portable fix?

Thanks,

Bradford