Not able to filter containers by 'auto_remove'

[hongbin]

Description
===========
List containers and filter the container by 'auto_remove' but the response is unexpected.

Reproduce
=========
$ source /opt/stack/devstack/openrc demo demo
$ zun run --auto-remove nginx
$ TOKEN=$(openstack token issue | awk '/ id /{print $4}')
$ curl -g -i -X GET "http://172.31.10.218/container/v1/containers?auto_remove=True" -H "X-Auth-Token: $TOKEN" \
    -H "Content-Type: application/json" -H "Accept: application/json"
# empty list

$ curl -g -i -X GET "http://172.31.10.218/container/v1/containers?auto_remove=False" -H "X-Auth-Token: $TOKEN" \
    -H "Content-Type: application/json" -H "Accept: application/json"
# empty list

Expected
========
The first curl command returns an non-empty list, the second command returns an empty list

Actual
======
Both curl commands returns empty list