--- aruba-2.0.0/lib/aruba/api/bundler.rb.make_optional	2021-07-27 04:28:08.000000000 +0900
+++ aruba-2.0.0/lib/aruba/api/bundler.rb	2022-01-14 14:40:50.369324292 +0900
@@ -1,5 +1,4 @@
 require "aruba/api/environment"
-require "bundler"
 
 module Aruba
   module Api
@@ -8,6 +7,19 @@ module Aruba
 
       # Unset variables used by bundler
       def unset_bundler_env_vars
+        begin
+          require "bundler"
+          unset_bundler_env_vars_new
+        rescue LoadError
+          %w[RUBYOPT BUNDLE_PATH BUNDLE_BIN_PATH BUNDLE_GEMFILE].each do |key|
+            delete_environment_variable(key)
+          end
+        end
+      end
+
+      private
+
+      def unset_bundler_env_vars_new
         empty_env = with_environment { with_unbundled_env { ENV.to_h } }
         aruba_env = aruba.environment.to_h
         (aruba_env.keys - empty_env.keys).each do |key|
@@ -18,8 +30,6 @@ module Aruba
         end
       end
 
-      private
-
       def with_unbundled_env(&block)
         if ::Bundler.respond_to?(:with_unbundled_env)
           ::Bundler.with_unbundled_env(&block)