Closure compiler does not eliminate dead branches based on branching the goog.LOCALE setting. (File paths are converted to underscores in the file names)

build.clj

(require 'cljs.build.api)

(cljs.build.api/build "src"
  {:output-to "out/main.js"
   :optimizations :advanced
   :pretty-print    true
   :closure-defines {
                     'goog.DEBUG false
                     'goog.LOCALE "nl"}})

(System/exit 0)

out_main.js

// 20471 lines of javascript omitted
var i18n = {fr:{}};
i18n.fr.message = "French";
i18n.nl = {};
i18n.nl.message = "Dutch";
i18n.translate = {};
cljs.core.enable_console_print_BANG_.call(null);
i18n.translate.translation = function() {
  var a = cljs.core.identical_QMARK_, b = goog.LOCALE;
  return cljs.core.truth_(a.call(null, "nl", b)) ? i18n.nl.message : cljs.core.truth_(a.call(null, "fr", b)) ? i18n.fr.message : "unknown";
}();
cljs.core.println.call(null, "goog.LOCALE ", goog.LOCALE, " leads to translated text: ", i18n.translate.translation);

out_main_advanced.js

// I only included line 5364 of the 5406-line output
}(), Ee = x(za.a ? za.a("nl", "nl") : za.call(null, "nl", "nl")) ? "Dutch" : x(za.a ? za.a("fr", "nl") : za.call(null, "fr", "nl")) ? "French" : "unknown", Ge = fc(["goog.LOCALE ", "nl", " leads to translated text: ", Ee], 0), He = kc.g(qa(), ua, !1), Ie, Je;

src_i18n_fr.cljs

(ns i18n.fr)

(def message "French")

src_i18n_nl.cljs

(ns i18n.nl)

(def message "Dutch")

src_i18n_translate.cljs

(ns i18n.translate
  (:require [i18n.nl]
            [i18n.fr]))

(enable-console-print!)

(def translation (condp identical? js/goog.LOCALE
                  "nl" i18n.nl/message
                  "fr" i18n.fr/message
                  "unknown"))

(println "goog.LOCALE " js/goog.LOCALE " leads to translated text: " translation)

;; both the word "Dutch" from "src/i18n/nl.cljs" and the word
;; "French" from "src/i18n/fr.cljs" are present in the output.
;; 

The output is different when I use a case in the translate.cljs file, but the issue of having all the branches in the output remains:

(def translation (case js/goog.LOCALE
                  "nl" i18n.nl/message
                  "fr" i18n.fr/message
                  "unknown"))

De = ec(["goog.LOCALE ", "nl", " leads to translated text: ", function() {
  switch("nl") {
    case "nl":
      return "Dutch";
    case "fr":
      return "French";
    default:
      return "unknown";
  }
}()]