Ignore to add bundler lib direcotry if it is same as rubylibdir

lib/bundler/shared_helpers.rb

@@ -3,6 +3,7 @@
 require "bundler/compatibility_guard"
 
 require "pathname"
+require "rbconfig"
 require "rubygems"
 
 require "bundler/version"
@@ -341,7 +342,7 @@ def set_rubyopt
 
     def set_rubylib
       rubylib = (ENV["RUBYLIB"] || "").split(File::PATH_SEPARATOR)
-      rubylib.unshift bundler_ruby_lib
+      rubylib.unshift bundler_ruby_lib unless RbConfig::CONFIG["rubylibdir"] == bundler_ruby_lib
       Bundler::SharedHelpers.set_env "RUBYLIB", rubylib.uniq.join(File::PATH_SEPARATOR)
     end
 

spec/bundler/shared_helpers_spec.rb

@@ -261,6 +261,15 @@
       subject.set_bundle_environment
     end
 
+    it "ignores if bundler_ruby_lib is same as rubylibdir" do
+      allow(Bundler::SharedHelpers).to receive(:bundler_ruby_lib).and_return(RbConfig::CONFIG["rubylibdir"])
+
+      subject.set_bundle_environment
+
+      paths = (ENV["RUBYLIB"]).split(File::PATH_SEPARATOR)
+      expect(paths.count(RbConfig::CONFIG["rubylibdir"])).to eq(0)
+    end
+
     it "exits if bundle path contains the unix-like path separator" do
       if Gem.respond_to?(:path_separator)
         allow(Gem).to receive(:path_separator).and_return(":")