Insert header when item added to ramcache

There aren't any other rules or policies. I'd tried both insert and replace, but the logging in CACHE_RESPONSE never showed any effect from either of the UPDATE commands.

when CACHE_UPDATE {
  CACHE::header insert X-LTM-Cached $cache
  # CACHE::header replace Cache-Control $cache
}
when CACHE_RESPONSE {
  log local0. "[IP::client_addr] path:$path cache:$cache [CACHE::headers]"
}
when HTTP_REQUEST {
  set path [string tolower [HTTP::path]]
  if { !($path ends_with ".js") } {
    CACHE::disable
  } else {
      HTTP::uri [HTTP::path]
      CACHE::enable
  }
}
when HTTP_RESPONSE {
  set cache [HTTP::header value Cache-Control]
  HTTP::header replace Cache-Control public
}