post_get_test_node returns conductor_affinity attribute that is not exposed in API

ironic.tests.api.utils.node_post_data function is used to get a dictionary that is POST'ed in tests. It deletes all internal API attributes from node dictionary, but there is an attribute conductor_affinity, that is not present in API node at all (and therefore is not internal). Because of that, it's not filtered from that dictionary and gets POST'ed, and in API node's constructor is silently ignored because of this part of code:

if not hasattr(self, k):
    continue

While tests currently are not failing because of that, I guess it's not a correct behaviour.