Updated openstack/openstack
Project: openstack/oslo.messaging  821ee096a6b1dd897892af90b47738051d0fa8f4

Removes the use of mutables as default args

Passing mutable objects as default args is a known Python pitfall.
We'd better avoid this.

Change-Id: I67cc0774a65886ef9fce0b72e52157b622248a85
Closes-Bug: #1327473