You can request from gitblit, e.g. https://git.wikimedia.org/zip/?r=mediawiki/extensions/SyntaxHighlight_GeSHi&h=refs/heads/master&format=gz . Template:WikimediaDownload uses this to provide a (Git master) link, and via {{Extension}} it's used in hundreds of extensions.
It seems Diffusion doesn't offer an equivalent, I couldn't see it at https://phabricator.wikimedia.org/diffusion/ESHG/browse/master/ .