This is part of why I have some issue with the Golang packaging story, it pretty much requires you to refer to dependent packages as `host.com/user/pkg`, so in most cases it's `github.com/...`. You can manually rewrite this, but that's not really ideal.
In case whether 'search & replace' method is not an option you may create your own 'proxy' server like gopkg.in [1], since Golang packages don't have to be only on GitHub [2] you may set up mirroring rules to overcome problems with package location, version/revision, or library when GitHub downtime may occur. Personally, I don't think if creating own proxy server as solution would be quite big deal whether there are many various dependency tools for Go. 'Search & replace' is not mission impossible either. Go is not PHP - it just won't compile if (local) dependency is broken.
