Make sure that cloud always has a name

If we don't ask for a cloud, and we fall through to the envvars cloud or
the defaults cloud, the cloud that is returned winds up not being named
- even though we know what cloud it is. Set the name of the cloud we're
working with.

This is important for the next patch, where we need to peek at the
config to get some default values, but in a fallthrough case we do not
know which cloud to request.

Change-Id: Ie56e490d4384f2d680450bc956e4b7b5b8099f0e

os_client_config/config.py

@@ -177,6 +177,8 @@ class OpenStackConfig(object):
         envvars = _get_os_environ(envvar_prefix=envvar_prefix)
         if envvars:
             self.cloud_config['clouds'][self.envvar_key] = envvars
+            if not self.default_cloud:
+                self.default_cloud = self.envvar_key
 
         # Finally, fall through and make a cloud that starts with defaults
         # because we need somewhere to put arguments, and there are neither
@@ -184,6 +186,7 @@ class OpenStackConfig(object):
         if not self.cloud_config['clouds']:
             self.cloud_config = dict(
                 clouds=dict(defaults=dict(self.defaults)))
+            self.default_cloud = 'defaults'
 
         self._cache_expiration_time = 0
         self._cache_path = CACHE_PATH
@@ -604,14 +607,14 @@ class OpenStackConfig(object):
             on missing required auth parameters
         """
 
-        if cloud is None and self.default_cloud:
-            cloud = self.default_cloud
-
-        if cloud is None and self.envvar_key in self.get_cloud_names():
-            cloud = self.envvar_key
-
         args = self._fix_args(kwargs, argparse=argparse)
 
+        if cloud is None:
+            if 'cloud' in args:
+                cloud = args['cloud']
+            else:
+                cloud = self.default_cloud
+
         if 'region_name' not in args or args['region_name'] is None:
             args['region_name'] = self._get_region(cloud)