Don't replace ENV twice on non Windows platforms

bundler/lib/bundler/environment_preserver.rb

@@ -38,7 +38,10 @@ def initialize(env, keys)
 
     # Replaces `ENV` with the bundler environment variables backed up
     def replace_with_backup
-      ENV.replace(backup) unless Gem.win_platform?
+      unless Gem.win_platform?
+        ENV.replace(backup)
+        return
+      end
 
       # Fallback logic for Windows below to workaround
       # https://bugs.ruby-lang.org/issues/16798. Can be dropped once all

bundler/spec/realworld/ffi_spec.rb

@@ -0,0 +1,57 @@
+# frozen_string_literal: true
+
+RSpec.describe "loading dinamically linked library on a bundle exec context", :realworld => true do
+  it "passes ENV right after argv in memory" do
+    create_file "foo.rb", <<~RUBY
+      require 'ffi'
+
+      module FOO
+        extend FFI::Library
+        ffi_lib './libfoo.so'
+
+        attach_function :Hello, [], :void
+      end
+
+      FOO.Hello()
+    RUBY
+
+    create_file "libfoo.c", <<~'C'
+      #include <stdio.h>
+
+      static int foo_init(int argc, char** argv, char** envp) {
+        if (argv[argc+1] == NULL) {
+          printf("FAIL\n");
+        } else {
+          printf("OK\n");
+        }
+
+        return 0;
+      }
+
+      #if defined(__APPLE__) && defined(__MACH__)
+      __attribute__((section("__DATA,__mod_init_func"), used, aligned(sizeof(void*))))
+      #else
+      __attribute__((section(".init_array")))
+      #endif
+      static void *ctr = &foo_init;
+
+      extern char** environ;
+
+      void Hello() {
+        return;
+      }
+    C
+
+    sys_exec "gcc -g -o libfoo.so -shared -fpic libfoo.c"
+
+    install_gemfile <<-G
+      source "https://rubygems.org"
+
+      gem 'ffi'
+    G
+
+    bundle "exec ruby foo.rb"
+
+    expect(out).to eq("OK")
+  end
+end

bundler/spec/support/artifice/vcr_cassettes/realworld/rubygems.org/gems/ffi-1.15.4.gem/GET/request

@@ -0,0 +1,7 @@
+> GET /gems/ffi-1.15.4.gem
+> accept-encoding: gzip;q=1.0,deflate;q=0.6,identity;q=0.3
+> accept: */*
+> user-agent: Ruby
+> connection: keep-alive
+> keep-alive: 30
+> host: rubygems.org