class Gem::Resolver::GitSpecification

def install options = {}
  require 'rubygems/installer'
  installer = Gem::Installer.for_spec spec, options
  yield installer if block_given?
  installer.run_pre_install_hooks
  installer.build_extensions
  installer.run_post_build_hooks
  installer.generate_bin
  installer.run_post_install_hooks
end