This is essentially a variant of push-ci-build.sh, but pushes it to
the current project. The defaults for gcs::release actually pick a
shorthash of the GCS project, so you end up uploading to something
like: gs://kubernetes-releases-3fda2/devel/v0.8.0-437-g7f147ed/ (where
the last part is the "git describe" of your current commit)