Ask HN: How to deploy to a customer that doesn't have access to your repo?

I need to support multiple deployments to various customers. Their servers could be on anything.

I can access them, but I don't want them to be able to directly checkout code from my Github repo.

The only tool I'm familiar with is Capistrano, and as far as I know, requires access on the production machine to the source control repository. That's not what I want in this situation... Any ideas or suggestions?