Sync rpc/impl_qpid.py from oslo-incubator.

Fixes bug #1211338 (seen in Neutron, marked in launchpad as oslo
since the bug was in oslo code).

Change-Id: I11971c1213b095979bd4f2e878ea2bcad3ceb617
Merge "Sync rpc/impl_qpid.py from oslo-incubator."