The ssh_broker requires a fairly new verion of go along with the ssh package. Pull the latest with: hg clone -u release https://code.google.com/p/go

Or update if you have it. Go version 1.3.3 or later works fine. You'll also need to get the crypto package in order to get the ssh support: cd $GOPATH go get golang.org/x/crypto/ssh

Related doc: https://godoc.org/golang.org/x/crypto/ssh