Guard the vendored pub_grub against double loading

When the same Gem::PubGrub copy is shipped in two gems (RubyGems and
Bundler) and required from different paths, the unguarded entrypoint
reloads it and emits "already initialized constant" warnings. Add an
idempotent guard at the top of the vendored pub_grub.rb so a second load
from any path short-circuits before requiring any subfile. This prepares
Bundler to reuse RubyGems' copy.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: 2 people

lib/rubygems/vendor/pub_grub/lib/pub_grub.rb

@@ -1,3 +1,7 @@
+# Skip reloading when an identical copy (e.g. the one shipped inside the Bundler
+# gem) was already required from a different path, to avoid redefinition warnings.
+return if defined?(Gem::PubGrub::VERSION)
+
 require_relative "pub_grub/package"
 require_relative "pub_grub/static_package_source"
 require_relative "pub_grub/term"

tool/automatiek/pub_grub-rubygems.patch

@@ -1,7 +1,15 @@
 diff --git a/lib/rubygems/vendor/pub_grub/lib/pub_grub.rb b/lib/rubygems/vendor/pub_grub/lib/pub_grub.rb
 --- a/lib/rubygems/vendor/pub_grub/lib/pub_grub.rb
 +++ b/lib/rubygems/vendor/pub_grub/lib/pub_grub.rb
-@@ -11,6 +11,32 @@
+@@ -1,3 +1,7 @@
++# Skip reloading when an identical copy (e.g. the one shipped inside the Bundler
++# gem) was already required from a different path, to avoid redefinition warnings.
++return if defined?(Gem::PubGrub::VERSION)
++
+ require_relative "pub_grub/package"
+ require_relative "pub_grub/static_package_source"
+ require_relative "pub_grub/term"
+@@ -11,6 +15,32 @@
  require_relative 'pub_grub/version'
 
  module Gem::PubGrub