Deploy to GitHub without git config --global

[eric-hc]

Somewhat of a discussion in #1771, but I was wondering if anyone has been able to deploy to gh-pages without setting a global git config. I am trying this, but have not had any luck yet.

export GIT_USER={...}
git config user.name {...}
git config user.email {...}

I am even setting {user}:{key} for the GIT_USER environment variable, and tried setting them in a .gitconfig file, but the deploy script still wants global git config.