Updated openstack/openstack
Project: openstack/oslo.messaging  588f63907146700b5932380ab5764e2edce257f9
null
Fixed the issue for pop exception

Fixed the issue so that two
threads do not pop the list at the same time
Closes-Bug: #1283926
Change-Id: I693407495c18c3e4a0ca2d8d94c4f4ed179371bf