Test that copy_from is used properly in old API

This adds a test to verify that the copy from attribute is used
properly.  It tests for bug 1167899.  This submission depends on
the review here: https://review.openstack.org/#/c/26740/

Change-Id: Ied14fb29887b7cbbecbab51bd384cf0f640c9e18
Merge "Test that copy_from is used properly in old API"