[rubygems/rubygems] Fix bundler/inline overwriting lockfiles

This was introduced by https://github.com/rubygems/rubygems/commit/0b7be7bb7705, because
the original patch was not adapted to some recent refactorings.

https://github.com/rubygems/rubygems/commit/0bca60d6e5

Co-authored-by: Hiroshi SHIBATA <hsbt@ruby-lang.org>

lib/bundler/definition.rb

@@ -317,7 +317,7 @@ module Bundler
 
     def lock(file_or_preserve_unknown_sections = false, preserve_unknown_sections_or_unused = false)
       if [true, false, nil].include?(file_or_preserve_unknown_sections)
-        target_lockfile = lockfile || Bundler.default_lockfile
+        target_lockfile = lockfile
         preserve_unknown_sections = file_or_preserve_unknown_sections
       else
         target_lockfile = file_or_preserve_unknown_sections

spec/bundler/runtime/inline_spec.rb

@@ -656,6 +656,20 @@ RSpec.describe "bundler/inline#gemfile" do
     expect(out).to include("after: [\"Test_Variable\"]")
   end
 
+  it "does not create a lockfile" do
+    script <<-RUBY
+      require 'bundler/inline'
+
+      gemfile do
+        source "https://gem.repo1"
+      end
+
+      puts Dir.glob("Gemfile.lock")
+    RUBY
+
+    expect(out).to be_empty
+  end
+
   it "does not load specified version of psych and stringio", :ruby_repo do
     build_repo4 do
       build_gem "psych", "999"
@@ -678,4 +692,25 @@ RSpec.describe "bundler/inline#gemfile" do
     expect(out).to include("The psych gem was resolved to 999")
     expect(out).to include("The stringio gem was resolved to 999")
   end
+
+  it "leaves a lockfile in the same directory as the inline script alone" do
+    install_gemfile <<~G
+      source "https://gem.repo1"
+      gem "foo"
+    G
+
+    original_lockfile = lockfile
+
+    script <<-RUBY, env: { "BUNDLER_SPEC_GEM_REPO" => gem_repo1.to_s }
+      require "bundler/inline"
+
+      gemfile(true) do
+        source "https://gem.repo1"
+
+        gem "myrack"
+      end
+    RUBY
+
+    expect(lockfile).to eq(original_lockfile)
+  end
 end