This patch fixes two unit test errors. One is "ipv6_address_mode not
found", the other is "has no attribute type_manager". The first error
is addressed by the previous patch[1] but cannot be merged due to the
second error, so this patch address these two errors at the same time.
[1] https://review.openstack.org/#/c/532417/
Change-Id: Ibda5b5870fa8466b3f5a886ee0c16a2ec8c74abc