Configuration overrides via environment variable

Hi,

I'm using Git in some scripts, and wanted to get its colorised output even when it is not going to a tty. I don't want to permanently change ~/.gitconfig or the per-repo config; I just want to set color.status (and perhaps others) to "always" for a one-off run. I suppose I could munge the config files, storing the previous value and restoring it later, but that's messy.

Ideally, an environment variable like GIT_EXTRA_CONFIG or something would be nice, so I could just do:

GIT_EXTRA_CONFIG="color.status=always" git status | ...

Thoughts? Does this already exist, and I've overlooked it?

Dave.