Cannot update the quotas for a quota class

Cannot update the quotas for a quota class.

Steps to reproduce:
1. Execute 'manila -d quota-class-update abc --shares <some_value>' command

Expected result:
The quotas for a quota class are updated. The HTTP response is 200.

Actual result:
Getting an error:
DEBUG (shell:510) 'Namespace' object has no attribute 'class_name'
Traceback (most recent call last):
  File "/opt/stack/python-manilaclient/manilaclient/shell.py", line 505, in main
    map(encodeutils.safe_decode, sys.argv[1:]))
  File "/opt/stack/python-manilaclient/manilaclient/shell.py", line 453, in main
    args.func(self.cs, args)
  File "/opt/stack/python-manilaclient/manilaclient/v1/shell.py", line 407, in do_quota_class_update
    _quota_update(cs.quota_classes, args.class_name, args)
AttributeError: 'Namespace' object has no attribute 'class_name'
ERROR: 'Namespace' object has no attribute 'class_name'