def server_errors
      [
        OpenSSL::SSL::SSLError,
        Errno::ETIMEDOUT,
        Errno::EHOSTUNREACH,
        Errno::ENETUNREACH,
        Errno::ECONNRESET,
        Net::OpenTimeout,
        SocketError,
        Net::HTTPServerError
      ] + extra_server_errors
    end
def server_errors
      [
        OpenSSL::SSL::SSLError,
        Errno::ETIMEDOUT,
        Errno::EHOSTUNREACH,
        Errno::ENETUNREACH,
        Errno::ECONNRESET,
        Net::OpenTimeout,
        SocketError,
        Net::HTTPServerError
      ] + extra_server_errors
    end
Returns the list of server errors worth retrying the request once.