git credential cache and sudo

When I do sudo git pull, git does not know about my credential cache.

On some servers, when I do a sudo -E git pull, it can find my credential cache and use it. On other servers, I think the sudo configuration is stripping the environment, so this doesn't work and I still have to enter my git credentials.

What environment variables do I need to configure sudo to preserve to make sudo -E git pull work with my credential cache? Or is there something else I can pass to git or define to get it to use my credential cache?

Thanks.

--John