gistfile1.txt

diff --git a/nova/tests/functional/api/client.py b/nova/tests/functional/api/client.py
index db4d58c..fed8172 100644
--- a/nova/tests/functional/api/client.py
+++ b/nova/tests/functional/api/client.py
@@ -169,7 +169,16 @@ class TestOpenStackClient(object):
         headers = kwargs.setdefault('headers', {})
         headers['X-Auth-Token'] = auth_result['x-auth-token']
         if self.microversion:
+            if ('X-OpenStack-Nova-API-Version' in headers and
+                    headers['X-OpenStack-Nova-API-Version'] != \
+                            self.microversion):
+                raise Exception('Invalid to set X-OpenStack-Nova-API-Version '
+                                'in headers and also as microversion '
+                                'attribute when the values are different.')
             headers['X-OpenStack-Nova-API-Version'] = self.microversion
+        elif 'X-OpenStack-Nova-API-Version' in headers:
+            raise Exception('Set X-OpenStack-Nova-API-Version header using '
+                            'microversion attribute on api client.')
 
         response = self.request(full_uri, **kwargs)
 
user@xubuntu:~/git/nova$