[rubygems/rubygems] Allow bundle pristine to run in parallel

Also fix running when BUNDLE_NO_INSTALL happens to be set, same as with install/update commands

https://github.com/rubygems/rubygems/commit/a555fd6ccd

lib/bundler/cli.rb

@@ -660,8 +660,10 @@ module Bundler
     D
     def pristine(*gems)
       require_relative "cli/pristine"
+      Bundler.settings.temporary(no_install: false) do
         Pristine.new(gems).run
       end
+    end
 
     if Bundler.feature_flag.plugins?
       require_relative "cli/plugin"

lib/bundler/cli/pristine.rb

@@ -12,7 +12,8 @@ module Bundler
       definition.validate_runtime!
       installer = Bundler::Installer.new(Bundler.root, definition)
 
-      Bundler.load.specs.each do |spec|
+      ProcessLock.lock do
+        installed_specs = definition.specs.reject do |spec|
           next if spec.name == "bundler" # Source::Rubygems doesn't install bundler
           next if !@gems.empty? && !@gems.include?(spec.name)
 
@@ -45,7 +46,14 @@ module Bundler
             next
           end
 
-        Bundler::GemInstaller.new(spec, installer, false, 0, true).install_from_spec
+          true
+        end.map(&:name)
+
+        jobs = installer.send(:installation_parallelization, {})
+        pristine_count = definition.specs.count - installed_specs.count
+        # allow a pristining a single gem to skip the parallel worker
+        jobs = [jobs, pristine_count].min
+        ParallelInstaller.call(installer, definition.specs, jobs, false, true, skip: installed_specs)
       end
     end
   end

lib/bundler/installer/parallel_installer.rb

@@ -62,20 +62,23 @@ module Bundler
       end
     end
 
-    def self.call(*args)
-      new(*args).call
+    def self.call(*args, **kwargs)
+      new(*args, **kwargs).call
     end
 
     attr_reader :size
 
-    def initialize(installer, all_specs, size, standalone, force)
+    def initialize(installer, all_specs, size, standalone, force, skip: nil)
       @installer = installer
       @size = size
       @standalone = standalone
       @force = force
       @specs = all_specs.map {|s| SpecInstallation.new(s) }
+      @specs.each do |spec_install|
+        spec_install.state = :installed if skip.include?(spec_install.name)
+      end if skip
       @spec_set = all_specs
-      @rake = @specs.find {|s| s.name == "rake" }
+      @rake = @specs.find {|s| s.name == "rake" unless s.installed? }
     end
 
     def call