do_install

# File lib/bundler/installer/parallel_installer.rb, line 158
    def do_install(spec_install, worker_num)
      Plugin.hook(Plugin::Events::GEM_BEFORE_INSTALL, spec_install)
      gem_installer = Bundler::GemInstaller.new(
        spec_install.spec, @installer, @standalone, worker_num, @force
      )
      success, message = begin
        gem_installer.install_from_spec
      rescue RuntimeError => e
        raise e, "#{e}\n\n#{require_tree_for_spec(spec_install.spec)}"
      end
      if success
        spec_install.state = :installed
        spec_install.post_install_message = message unless message.nil?
      else
        spec_install.state = :failed
        spec_install.error = "#{message}\n\n#{require_tree_for_spec(spec_install.spec)}"
      end
      Plugin.hook(Plugin::Events::GEM_AFTER_INSTALL, spec_install)
      spec_install
    end