image can't be registered without description parameter

Attempts to register image without description parameter lead to the following error:

2015-10-27 14:38:24.698 9351 ERROR sahara.utils.api [req-4c2eac72-ffb1-4a7e-8274-8402772066e5 ] Request aborted with status code 500 and message 'Internal Server Error'
2015-10-27 14:38:24.699 9351 ERROR sahara.utils.api [req-4c2eac72-ffb1-4a7e-8274-8402772066e5 ] Traceback (most recent call last):
  File "/home/kshatrix/sahara/sahara/utils/api.py", line 97, in handler
    return func(**kwargs)
  File "/home/kshatrix/sahara/sahara/api/acl.py", line 43, in handler
    return func(*args, **kwargs)
  File "/home/kshatrix/sahara/sahara/service/validation.py", line 76, in handler
    return func(*args, **kwargs)
  File "/home/kshatrix/sahara/sahara/service/validation.py", line 47, in handler
    return func(*args, **kwargs)
  File "/home/kshatrix/sahara/sahara/api/v10.py", line 239, in images_set
    return u.render(api.register_image(image_id, **data).wrapped_dict)
  File "/home/kshatrix/sahara/sahara/service/api.py", line 284, in register_image
    client.images.set_description, image_id, username, description)
  File "/home/kshatrix/sahara/sahara/utils/openstack/base.py", line 101, in execute_with_retries
    raise e
BadRequest: Invalid input for field/attribute _sahara_description. Value: None. None is not of type 'string' (HTTP 400) (Request-ID: req-83bebc2a-b916-407f-b9dd-017bc7128e07)