[rubygems/rubygems] Ignore dependencies not actually locked from frozen check

Only needed if there can be no explicit global source (bundler < 3).

https://github.com/rubygems/rubygems/commit/73923f4af5

lib/bundler/definition.rb

@@ -379,7 +379,12 @@ module Bundler
 
       both_sources = Hash.new {|h, k| h[k] = [] }
       @dependencies.each {|d| both_sources[d.name][0] = d }
-      locked_dependencies.each {|d| both_sources[d.name][1] = d }
+
+      locked_dependencies.each do |d|
+        next if !Bundler.feature_flag.bundler_3_mode? && @locked_specs[d.name].empty?
+
+        both_sources[d.name][1] = d
+      end
 
       both_sources.each do |name, (dep, lock_dep)|
         next if dep.nil? || lock_dep.nil?

spec/bundler/install/deploy_spec.rb

@@ -258,6 +258,17 @@ RSpec.describe "install in deployment or frozen mode" do
       expect(out).to eq("WIN")
     end
 
+    it "works if a gem is missing, but it's on a different platform, and the Gemfile has no global source", :bundler => "< 3" do
+      install_gemfile <<-G
+        source "#{file_uri_for(gem_repo1)}" do
+          gem "rake", platform: :#{not_local_tag}
+        end
+      G
+
+      bundle :install, :env => { "BUNDLE_FROZEN" => "true" }
+      expect(last_command).to be_success
+    end
+
     it "explodes if a path gem is missing" do
       build_lib "path_gem"
       install_gemfile <<-G