class Gem::Commands::UpdateCommand

def fetch_remote_gems(spec) # :nodoc:
  dependency = Gem::Dependency.new spec.name, "> #{spec.version}"
  dependency.prerelease = options[:prerelease]
  fetcher = Gem::SpecFetcher.fetcher
  spec_tuples, errors = fetcher.search_for_dependency dependency
  error = errors.find {|e| e.respond_to? :exception }
  raise error if error
  spec_tuples
end