Remove hard-coded policy choices for creating a server group

The hard-coded choices for the server group policy make it impossible
to create a server group with the soft-affinity or
soft-anti-affinity policy rules which were added in compute API
microversion 2.15. This removes the hard-coded choices so that the
policy is restricted on the server side rather than the client side.

Change-Id: Ib3dc39422ac1015872d56ae2fdeddf0f29613494
Closes-Bug: #1732938

openstackclient/compute/v2/server_group.py

@@ -55,11 +55,12 @@ class CreateServerGroup(command.ShowOne):
         parser.add_argument(
             '--policy',
             metavar='<policy>',
-            choices=['affinity', 'anti-affinity'],
             default='affinity',
             help=_("Add a policy to <name> "
                    "('affinity' or 'anti-affinity', "
-                   "default to 'affinity')")
+                   "defaults to 'affinity'). Specify --os-compute-api-version "
+                   "2.15 or higher for the 'soft-affinity' or "
+                   "'soft-anti-affinity' policy.")
         )
         return parser
 

openstackclient/tests/unit/compute/v2/test_server_group.py

@@ -63,11 +63,11 @@ class TestServerGroupCreate(TestServerGroup):
 
     def test_server_group_create(self):
         arglist = [
-            '--policy', 'anti-affinity',
+            '--policy', 'soft-anti-affinity',
             'affinity_group',
         ]
         verifylist = [
-            ('policy', 'anti-affinity'),
+            ('policy', 'soft-anti-affinity'),
             ('name', 'affinity_group'),
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)