Update bundled bundler to 1.16.0.

* lib/bundler, spec/bundler: Merge bundler-1.16.0.
  * common.mk: rspec examples of bundler-1.16.0 needs require option.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60603 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

spec/bundler/install/process_lock_spec.rb

@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+RSpec.describe "process lock spec" do
+  describe "when an install operation is already holding a process lock" do
+    before { FileUtils.mkdir_p(default_bundle_path) }
+
+    it "will not run a second concurrent bundle install until the lock is released" do
+      thread = Thread.new do
+        Bundler::ProcessLock.lock(default_bundle_path) do
+          sleep 1 # ignore quality_spec
+          expect(the_bundle).not_to include_gems "rack 1.0"
+        end
+      end
+
+      install_gemfile! <<-G
+        source "file://#{gem_repo1}"
+        gem "rack"
+      G
+
+      thread.join
+      expect(the_bundle).to include_gems "rack 1.0"
+    end
+  end
+end