[rubygems/rubygems] Avoid duplicates -rbundler/setup in RUBYOPT with Ruby preview

When using a Ruby preview the require path of `bundler/setup` is
similar to `-r/opt/ruby3.3.0-preview2/lib/ruby/3.3.0+0/bundler/setup`.
The special character `+` in the string makes the Regexp fail,
leading to multiple addition of the same require statement each time
`set_rubyopt` is called (e.g. server reloading).
Escaping the characters in the string esure a correct match with all
the different Ruby versions.

https://github.com/rubygems/rubygems/commit/dd43dfa709

lib/bundler/shared_helpers.rb

@@ -312,7 +312,7 @@ module Bundler
     def set_rubyopt
       rubyopt = [ENV["RUBYOPT"]].compact
       setup_require = "-r#{File.expand_path("setup", __dir__)}"
-      return if !rubyopt.empty? && rubyopt.first =~ /#{setup_require}/
+      return if !rubyopt.empty? && rubyopt.first =~ /#{Regexp.escape(setup_require)}/
       rubyopt.unshift setup_require
       Bundler::SharedHelpers.set_env "RUBYOPT", rubyopt.join(" ")
     end

spec/bundler/bundler/shared_helpers_spec.rb

@@ -242,7 +242,7 @@ RSpec.describe Bundler::SharedHelpers do
     shared_examples_for "ENV['RUBYOPT'] gets set correctly" do
       it "ensures -rbundler/setup is at the beginning of ENV['RUBYOPT']" do
         subject.set_bundle_environment
-        expect(ENV["RUBYOPT"].split(" ")).to start_with("-r#{source_lib_dir}/bundler/setup")
+        expect(ENV["RUBYOPT"].split(" ")).to start_with("-r#{install_path}/bundler/setup")
       end
     end
 
@@ -367,20 +367,41 @@ RSpec.describe Bundler::SharedHelpers do
       end
     end
 
-    context "ENV['RUBYOPT'] does not exist" do
-      before { ENV.delete("RUBYOPT") }
+    context "when bundler install path is standard" do
+      let(:install_path) { source_lib_dir }
 
-      it_behaves_like "ENV['RUBYOPT'] gets set correctly"
+      context "ENV['RUBYOPT'] does not exist" do
+        before { ENV.delete("RUBYOPT") }
+
+        it_behaves_like "ENV['RUBYOPT'] gets set correctly"
+      end
+
+      context "ENV['RUBYOPT'] exists without -rbundler/setup" do
+        before { ENV["RUBYOPT"] = "-I/some_app_path/lib" }
+
+        it_behaves_like "ENV['RUBYOPT'] gets set correctly"
+      end
+
+      context "ENV['RUBYOPT'] exists and contains -rbundler/setup" do
+        before { ENV["RUBYOPT"] = "-rbundler/setup" }
+
+        it_behaves_like "ENV['RUBYOPT'] gets set correctly"
+      end
     end
 
-    context "ENV['RUBYOPT'] exists without -rbundler/setup" do
-      before { ENV["RUBYOPT"] = "-I/some_app_path/lib" }
+    context "when bundler install path contains special characters" do
+      let(:install_path) { "/opt/ruby3.3.0-preview2/lib/ruby/3.3.0+0" }
 
-      it_behaves_like "ENV['RUBYOPT'] gets set correctly"
-    end
+      before do
+        ENV["RUBYOPT"] = "-r#{install_path}/bundler/setup"
+        allow(File).to receive(:expand_path).and_return("#{install_path}/bundler/setup")
+        allow(Gem).to  receive(:bin_path).and_return("#{install_path}/bundler/setup")
+      end
 
-    context "ENV['RUBYOPT'] exists and contains -rbundler/setup" do
-      before { ENV["RUBYOPT"] = "-rbundler/setup" }
+      it "ensures -rbundler/setup is not duplicated" do
+        subject.set_bundle_environment
+        expect(ENV["RUBYOPT"].split(" ").grep(%r{-r.*/bundler/setup}).length).to eq(1)
+      end
 
       it_behaves_like "ENV['RUBYOPT'] gets set correctly"
     end