Gem::GemcutterUtilities#host

# File tmp/rubies/ruby-3.4.1/lib/rubygems/gemcutter_utilities.rb, line 73
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&.empty?

      env_rubygems_host || configured_host
    end
end