Fix wrapping of neutron forbidden error

In neutronv2 api, the neutron forbidden error is not wrapped
correctly. The exception class expects the first parameter as
the error message but an exception object is passed.

Closes-Bug: #1720726
Change-Id: I6e88333427ec2befe2122274b02775f013404e30

nova/network/neutronv2/api.py

@@ -127,7 +127,7 @@ class ClientWrapper(clientv20.Client):
                           "admin credential located in nova.conf")
                 raise exception.NeutronAdminCredentialConfigurationInvalid()
             except neutron_client_exc.Forbidden as e:
-                raise exception.Forbidden(e)
+                raise exception.Forbidden(six.text_type(e))
             return ret
         return wrapper
 

nova/tests/unit/network/test_neutronv2.py

@@ -181,9 +181,10 @@ class TestNeutronClient(test.NoDBTestCase):
                                             auth_token='token',
                                             is_admin=False)
         client = neutronapi.get_client(my_context)
-        self.assertRaises(
+        exc = self.assertRaises(
             exception.Forbidden,
             client.create_port)
+        self.assertIsInstance(exc.format_message(), six.text_type)
 
     def test_withtoken_context_is_admin(self):
         self.flags(url='http://anyhost/', group='neutron')