How to block if Nomad variable key doesn't exists?

With the new nomad var syntax in consul-tempate and the template{} block, how does one replicates the consul KV behaviour where template blocks if key not found?

It seems like now it’s only possible to block when the whole variable path is missing:

{{ with nomadVar "nomad/jobs/job1" }}     <- blocks if "nomad/job/job1" is missing
{{ .KEY }} = {{ .VALUE }}                 <- doesn't block if KEY is missing
{{ end }}

Am I missing some consul-template foo here?