glanceclient has the same problem:

$ openstack image save 67fba704-a2f2-4cb4-a681-f12ff7674b74
Traceback (most recent call last):                                                                                                                                                            │····················
  File "/usr/lib/python2.7/site-packages/osc_lib/shell.py", line 134, in run                                                                                                                  │····················
    ret_val = super(OpenStackShell, self).run(argv)                                                                                                                                           │····················
  File "/usr/lib/python2.7/site-packages/cliff/app.py", line 279, in run                                                                                                                      │····················
    result = self.run_subcommand(remainder)                                                                                                                                                   │····················
  File "/usr/lib/python2.7/site-packages/osc_lib/shell.py", line 169, in run_subcommand                                                                                                       │····················
    ret_value = super(OpenStackShell, self).run_subcommand(argv)                                                                                                                              │····················
  File "/usr/lib/python2.7/site-packages/cliff/app.py", line 400, in run_subcommand                                                                                                           │····················
    result = cmd.run(parsed_args)                                                                                                                                                             │····················
  File "/usr/lib/python2.7/site-packages/osc_lib/command/command.py", line 41, in run                                                                                                         │····················
    return super(Command, self).run(parsed_args)                                                                                                                                              │····················
  File "/usr/lib/python2.7/site-packages/cliff/command.py", line 137, in run                                                                                                                  │····················
    return_code = self.take_action(parsed_args) or 0                                                                                                                                          │····················
  File "/usr/lib/python2.7/site-packages/openstackclient/image/v2/image.py", line 652, in take_action                                                                                         │····················
    gc_utils.save_image(data, parsed_args.file)                                                                                                                                               │····················
  File "/usr/lib/python2.7/site-packages/glanceclient/common/utils.py", line 286, in save_image                                                                                               │····················
    for chunk in data:                                                                                                                                                                        │····················
TypeError: 'NoneType' object is not iterable