Add location header to response mocks

Our unitests were broken by some outside change.
This patch fixes the issue.

Change-Id: I824fa4874e74aea4cfdd3720dd70e9db7801a024

vmware_nsxlib/tests/unit/v3/nsxlib_testcase.py

@@ -280,6 +280,7 @@ class NsxClientTestCase(NsxLibTestCase):
                 # record calls at the requests HTTP adapter level
                 mock_response = mock.Mock()
                 mock_response.history = None
+                mock_response.headers = {'location': ''}
                 # needed to bypass requests internal checks for mock
                 mock_response.raw._original_response = {}