The functional-api job sometimes fails

[hongbin]

Quoted from @Corey:

The functional-api job sometimes fails because bays timeout building after 1 hour. The logs look something like this:
magnum.tests.functional.api.v1.test_bay.BayTest.test_create_list_and_delete_bays [3733.626171s] ... FAILED
I can reproduce this hang on my devstack with etcdctl 2.0.10 as described in this bug (https://bugs.launchpad.net/magnum/+bug/1541105), but apparently either my fix with using 2.2.5 (https://review.openstack.org/#/c/275994/) is incomplete or there is another intermittent problem because it happened again even with that fix: (http://logs.openstack.org/94/275994/1/check/gate-functional-dsvm-magnum-api/32aacb1/console.html)