Gem::GemcutterUtilities#host

# File tmp/rubies/ruby-3.1.3/lib/rubygems/gemcutter_utilities.rb, line 66
def host
  configured_host = Gem.host unless
    Gem.configuration.disable_default_gem_server

  @host ||=
    begin
      env_rubygems_host = ENV["RUBYGEMS_HOST"]
      env_rubygems_host = nil if
        env_rubygems_host && env_rubygems_host.empty?

      env_rubygems_host || configured_host
    end
end