remove unnecessary conditionals

In several places we had else branches where a reasonable default
would do the job. This makes the code a mean cleaer and easier to
read.

Change-Id: I231e09aab85fd32b8300bc33c48d0899b728b96e

openstackclient/identity/v3/group.py

@@ -137,11 +137,11 @@ class CreateGroup(show.ShowOne):
     def take_action(self, parsed_args):
         self.log.debug('take_action(%s)', parsed_args)
         identity_client = self.app.client_manager.identity
+
+        domain = None
         if parsed_args.domain:
             domain = common.find_domain(identity_client,
                                         parsed_args.domain).id
-        else:
-            domain = None
 
         try:
             group = identity_client.groups.create(
@@ -228,11 +228,10 @@ class ListGroup(lister.Lister):
         self.log.debug('take_action(%s)', parsed_args)
         identity_client = self.app.client_manager.identity
 
+        domain = None
         if parsed_args.domain:
             domain = common.find_domain(identity_client,
                                         parsed_args.domain).id
-        else:
-            domain = None
 
         if parsed_args.user:
             user = utils.find_resource(

openstackclient/identity/v3/project.py

@@ -80,11 +80,10 @@ class CreateProject(show.ShowOne):
         self.log.debug('take_action(%s)', parsed_args)
         identity_client = self.app.client_manager.identity
 
+        domain = None
         if parsed_args.domain:
             domain = common.find_domain(identity_client,
                                         parsed_args.domain).id
-        else:
-            domain = None
 
         enabled = True
         if parsed_args.disable:

openstackclient/identity/v3/trust.py

@@ -92,23 +92,20 @@ class CreateTrust(show.ShowOne):
         self.log.debug('take_action(%s)' % parsed_args)
         identity_client = self.app.client_manager.identity
 
+        project_domain = None
         if parsed_args.project_domain:
             project_domain = common.find_domain(identity_client,
                                                 parsed_args.project_domain).id
-        else:
-            project_domain = None
 
+        trustor_domain = None
         if parsed_args.trustor_domain:
             trustor_domain = common.find_domain(identity_client,
                                                 parsed_args.trustor_domain).id
-        else:
-            trustor_domain = None
 
+        trustee_domain = None
         if parsed_args.trustee_domain:
             trustee_domain = common.find_domain(identity_client,
                                                 parsed_args.trustee_domain).id
-        else:
-            trustee_domain = None
 
         # NOTE(stevemar): Find the two users, project and roles that
         # are necessary for making a trust usable, the API dictates that

openstackclient/identity/v3/user.py

@@ -94,19 +94,17 @@ class CreateUser(show.ShowOne):
         self.log.debug('take_action(%s)', parsed_args)
         identity_client = self.app.client_manager.identity
 
+        project_id = None
         if parsed_args.project:
             project_id = utils.find_resource(
                 identity_client.projects,
                 parsed_args.project,
             ).id
-        else:
-            project_id = None
 
+        domain_id = None
         if parsed_args.domain:
             domain_id = common.find_domain(identity_client,
                                            parsed_args.domain).id
-        else:
-            domain_id = None
 
         enabled = True
         if parsed_args.disable:
@@ -211,11 +209,10 @@ class ListUser(lister.Lister):
         self.log.debug('take_action(%s)', parsed_args)
         identity_client = self.app.client_manager.identity
 
+        domain = None
         if parsed_args.domain:
             domain = common.find_domain(identity_client,
                                         parsed_args.domain).id
-        else:
-            domain = None
 
         if parsed_args.group:
             group = utils.find_resource(