def build
      trace "gem build #{gemspec}"
      spec = load_gemspec
      package = ::Gem::Package.build(spec)
      mkdir_p(pkgdir) unless File.directory?(pkgdir)
      mv(package, pkgdir)
    end
def build
      trace "gem build #{gemspec}"
      spec = load_gemspec
      package = ::Gem::Package.build(spec)
      mkdir_p(pkgdir) unless File.directory?(pkgdir)
      mv(package, pkgdir)
    end
Create a gem package.