Don't create empty quota set requests

The way that getattr is called with the None default you will always
create a compute_kwargs dictionary with key: None values. This means
that we will always send these empty requests to the servers.

Change so that only actually changed values end up in the quota set
requests and get sent.

Change-Id: I33bc3f4e1a8013ec672e995648d27513064baf26
Closes-Bug: #1451640

openstackclient/common/quota.py

@@ -97,8 +97,9 @@ class SetQuota(command.Command):
 
         compute_kwargs = {}
         for k, v in COMPUTE_QUOTAS.items():
-            if v in parsed_args:
-                compute_kwargs[k] = getattr(parsed_args, v, None)
+            value = getattr(parsed_args, v, None)
+            if value is not None:
+                compute_kwargs[k] = value
 
         volume_kwargs = {}
         for k, v in VOLUME_QUOTAS.items():