Homebrew I believe goes through GitHub. Many of the Vim plugin managers also do, or at least have the option. I think CocoaPods and Carthage, both for iOS development, do as well.
I think it's somewhat common for a new package manager to use Github as a kind of CDN for a while, until they get big enough they can do their own.
I think it's somewhat common for a new package manager to use Github as a kind of CDN for a while, until they get big enough they can do their own.