Fix py3k-unsafe code in test_get_properties()
Fix py3k-unsafe code in test_get_properties()

This changes the unit test test_get_properties() so that it is
py3k-safe.

This is a follow-up to a comment in review 107092:
https://review.openstack.org/#/c/107092/8/ironic/tests/drivers/test_ipmitool.py

Change-Id: I3fc1c9962d02516aa09b8c22f5c1f940a2173703

openstack/ironic,redhat-openstack/ironic,bacaldwell/ironic,faizan-barmawer/openstack_ironic,ionutbalutoiu/ironic,froyobin/ironic,debayanray/ironic_backup,SauloAislan/ironic,supermari0/ironic,ramineni/myironic,openstack/ironic,Tan0/ironic,naototty/vagrant-lxc-ironic,ionutbalutoiu/ironic,pshchelo/ironic,rackerlabs/ironic,hpproliant/ironic,naterh/ironic,rdo-management/ironic,SauloAislan/ironic,Tehsmash/ironic,dims/ironic,NaohiroTamura/ironic,devananda/ironic,pshchelo/ironic,naototty/vagrant-lxc-ironic,dims/ironic,NaohiroTamura/ironic,bacaldwell/ironic