Only rebuild latest if commit has changed
Only rebuild latest if commit has changed

Also store commit in the metadata of binaries in GCS so it's easy to figure out what commit they were built at.

kubernetes/minikube,warmchang/minikube,kubernetes/minikube,warmchang/minikube,warmchang/minikube,warmchang/minikube,warmchang/minikube,warmchang/minikube,kubernetes/minikube,warmchang/minikube,kubernetes/minikube,kubernetes/minikube,kubernetes/minikube,kubernetes/minikube