[rubygems/rubygems] Fix --prefer-local not respecting default gems

https://github.com/rubygems/rubygems/commit/3df86cd9c6

lib/bundler/definition.rb

@@ -220,6 +220,8 @@ module Bundler
 
     def prefer_local!
       @prefer_local = true
+
+      sources.prefer_local!
     end
 
     # For given dependency list returns a SpecSet with Gemspec of all the required

lib/bundler/installer.rb

@@ -193,7 +193,7 @@ module Bundler
     def install(options)
       standalone = options[:standalone]
       force = options[:force]
-      local = options[:local]
+      local = options[:local] || options[:"prefer-local"]
       jobs = installation_parallelization
       spec_installations = ParallelInstaller.call(self, @definition.specs, jobs, standalone, force, local: local)
       spec_installations.each do |installation|

lib/bundler/source.rb

@@ -35,6 +35,8 @@ module Bundler
       spec.source == self
     end
 
+    def prefer_local!; end
+
     def local!; end
 
     def local_only!; end

lib/bundler/source/rubygems.rb

@@ -19,6 +19,7 @@ module Bundler
         @allow_remote = false
         @allow_cached = false
         @allow_local = options["allow_local"] || false
+        @prefer_local = false
         @checksum_store = Checksum::Store.new
 
         Array(options["remotes"]).reverse_each {|r| add_remote(r) }
@@ -30,6 +31,10 @@ module Bundler
         @caches ||= [cache_path, *Bundler.rubygems.gem_cache]
       end
 
+      def prefer_local!
+        @prefer_local = true
+      end
+
       def local_only!
         @specs = nil
         @allow_local = true
@@ -37,6 +42,10 @@ module Bundler
         @allow_remote = false
       end
 
+      def local_only?
+        @allow_local && !@allow_remote
+      end
+
       def local!
         return if @allow_local
 
@@ -139,9 +148,15 @@ module Bundler
           index.merge!(cached_specs) if @allow_cached
           index.merge!(installed_specs) if @allow_local
 
-          # complete with default specs, only if not already available in the
+          if @allow_local
-          # index through remote, cached, or installed specs
+            if @prefer_local
-          index.use(default_specs) if @allow_local
+              index.merge!(default_specs)
+            else
+              # complete with default specs, only if not already available in the
+              # index through remote, cached, or installed specs
+              index.use(default_specs)
+            end
+          end
 
           index
         end

lib/bundler/source_list.rb

@@ -141,6 +141,10 @@ module Bundler
       different_sources?(lock_sources, replacement_sources)
     end
 
+    def prefer_local!
+      all_sources.each(&:prefer_local!)
+    end
+
     def local_only!
       all_sources.each(&:local_only!)
     end

spec/bundler/cache/gems_spec.rb

@@ -113,6 +113,11 @@ RSpec.describe "bundle cache" do
         expect(out).to include("Using json #{default_json_version}")
       end
 
+      it "does not use remote gems when installing with --prefer-local flag" do
+        install_gemfile %(source "https://gem.repo2"; gem 'json', '#{default_json_version}'), verbose: true, "prefer-local": true
+        expect(out).to include("Using json #{default_json_version}")
+      end
+
       it "caches remote and builtin gems" do
         install_gemfile <<-G
           source "https://gem.repo2"