Create QoS rule fails on python 3.5

[Slawek Kaplonski]

On python 3.5 there is error like can be observed on http://logs.openstack.org/52/478652/1/experimental/gate-neutron-dsvm-fullstack-python35-ubuntu-xenial-nv/f9d1ccc/logs/dsvm-fullstack-logs/TestBwLimitQoSLinuxbridge.test_bw_limit_direction_change_ingress_/neutron-server--2017-06-28--22-28-11-513301.txt.gz?level=ERROR#_2017-06-28_22_28_27_661

All QoS related full stack tests are failing because of this issue when running on python 3.5.
On python 2.7 there is no such error.

[YAMAMOTO Takashi (yamamoto)]

it's failing because NeutronDbObject is not hashable on python 3.5.

[Dong Jun (dongj)]

Here is a same issue[1] in networking-ovn for qos test, and a patch[2] submitted in oslo, but there is no approval or objection for a long time.
[1]https://review.openstack.org/#/c/460846/
[2]https://review.openstack.org/#/c/461726/

[Slawek Kaplonski (slaweq)]

So it looks that it's related to https://bugs.launchpad.net/oslo.versionedobjects/+bug/1687592

[Slawek Kaplonski (slaweq)]

Related fix is merged in Oslo.versionedobjects so it can be closed probably