The QPID driver's v2 topology was introduced to specifically address the slow growth of orphaned direct exchanges over time. By default, however, services still use the original v1 topology of the QPID driver; the v2 topology has to be explicitly configured via the 'qpid_topology_version = 2' parameter.
To address this, Packstack now adds the 'qpid_topology_version = 2' parameter to the distribution configuration file of each service (e.g. /usr/share/neutron/neutron-dist.conf). This effectively sets the QPID driver's v2 topology as the default.