cmd/hello: also redirect https://hello.ipn.dev to hello.ts.net

I apparently only did HTTP before, not HTTPS.

Updates tailscale/corp#1327

Change-Id: I7d5265a0a25fcab5b142c8c3f21a0920f6cae39f
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

cmd/hello/hello.go

@@ -161,6 +161,10 @@ func root(w http.ResponseWriter, r *http.Request) {
 		http.Redirect(w, r, "/", http.StatusFound)
 		return
 	}
+	if r.TLS != nil && *httpsAddr != "" && strings.Contains(r.Host, "hello.ipn.dev") {
+		http.Redirect(w, r, "https://hello.ts.net", http.StatusFound)
+		return
+	}
 	tmpl, err := getTmpl()
 	if err != nil {
 		w.Header().Set("Content-Type", "text/plain")