How to `go get` private repos using SSH key auth instead of password auth.

go_get_private_repos.txt

```bash
$ ssh -A vm
$ git config --global url."[email protected]:".insteadOf "https://github.com/"
$ cat ~/.gitconfig
[url "[email protected]:"]
	insteadOf = https://github.com/
$ go get github.com/private/repo && echo Success!
Success!
```

Sources:

- https://help.github.com/articles/which-remote-url-should-i-use #You can also use SSH agent forwarding with your deploy script to avoid managing keys on the server.
- http://golang.org/doc/faq #Why does "go get" use HTTPS when cloning a repository?
- https://www.kernel.org/pub/software/scm/git/docs/git-config.html #url.\<base\>.insteadOf