coredns: plugin/nsid: nsid not being set

Neither the default nor any other value is being set via nsid.

Tested with the following config:

. {
  forward . 8.8.8.8
  errors stdout
  log
  nsid test
  cache
}

. {
  forward . 8.8.8.8
  errors stdout
  log
  nsid
  cache
}

. {
  forward . 8.8.8.8
  errors stdout
  log
  nsid {$HOSTNAME}
  cache
}

Result:

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
; NSID