build should follow nodeConfig

Author: guybedford

lib/builder.js

@@ -154,7 +154,8 @@ Builder.prototype.reset = function(baseLoader) {
   loader.config = function(cfg) {
     loader.pluginLoader.config(cfg);
     var lCfg = extend({}, cfg);
-    lCfg.browserConfig = lCfg.nodeConfig = lCfg.productionConfig = undefined;
+    // build environment is not production or the browser, but will follow nodeConfig, because the build is in Node
+    lCfg.browserConfig = lCfg.productionConfig = undefined;
     loaderConfig.call(this, lCfg);
     loader.configHash = generateConfigHash(loader);
   };