Make sure to `require "rubygems"` explicitlyrequire_rubygems

Some setups have `--disable=gems` in `RUBYOPT`, and sometimes use
`bundler` without modifying that env. Let's not break those setups just
to save a `require`.

2 files changed, 8 insertions, 0 deletions

diff --git a/lib/bundler/rubygems_integration.rb b/lib/bundler/rubygems_integration.rb
index 17f2d7d9fa..f06e8d68a9 100644
--- a/lib/bundler/rubygems_integration.rb
+++ b/lib/bundler/rubygems_integration.rb
@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require "rubygems"
+
 module Bundler
   class RubygemsIntegration
     if defined?(Gem::Ext::Builder::CHDIR_MONITOR)
diff --git a/spec/runtime/setup_spec.rb b/spec/runtime/setup_spec.rb
index befc5f9d09..39240b7404 100644
--- a/spec/runtime/setup_spec.rb
+++ b/spec/runtime/setup_spec.rb
@@ -1344,5 +1344,11 @@ end
       expect(last_command.stdboth).not_to include "FAIL"
       expect(err).to include "private method `require'"
     end
+
+    it "takes care of requiring rubygems" do
+      sys_exec("#{Gem.ruby} -I#{lib_dir} -e \"puts require('bundler/setup')\"", "RUBYOPT" => "--disable=gems")
+
+      expect(last_command.stdboth).to eq("true")
+    end
   end
 end