Eventhub Override for on_open_async.

async def on_open_async(self):
        """
        Eventhub Override for on_open_async.
        """
        _opened_ok = False
        _retry_count = 0
        while (not _opened_ok) and (_retry_count < 5):
            try:
                await self.open_clients_async()
                _opened_ok = True
            except Exception as err:  # pylint: disable=broad-except
                _logger.warning(
                    "%r,%r PartitionPumpWarning: Failure creating client or receiver, retrying: %r",
                    self.host.guid, self.partition_context.partition_id, err)
                last_exception = err
                _retry_count += 1

        if not _opened_ok:
            await self.processor.process_error_async(self.partition_context, last_exception)
            self.set_pump_status("OpenFailed")

        if self.pump_status == "Opening":
            loop = asyncio.get_event_loop()
            self.set_pump_status("Running")
            await self.eh_client.run_async()
            self.running = loop.create_task(self.partition_receiver.run())

        if self.pump_status in ["OpenFailed", "Errored"]:
            self.set_pump_status("Closing")
            await self.clean_up_clients_async()
            self.set_pump_status("Closed")