Merge "parallelize add_partition_calls only if output_zip is None"

      ("system_dlkm", has_system_dlkm, AddSystemDlkm, []),

      ("system_other", has_system_other, AddSystemOther, []),

  )

  # If output_zip exists, each add_partition_calls writes bytes to the same output_zip,

  # which is not thread-safe. So, run them in serial if output_zip exists.

  if output_zip:

    for call in add_partition_calls:

      add_partition(*call)

  else:

    with ThreadPoolExecutor(max_workers=len(add_partition_calls)) as executor:

      for future in [executor.submit(add_partition, *call) for call in add_partition_calls]:

        future.result()