Use [ instead of [[.
This will solve the following issue:
Change-Id: I1153a5146ca8b08dd1ad732b60d8d4bce8e060ab
INFO:kolla.common.utils.neutron-base:/bin/sh: 1: [[: not found
INFO:kolla.common.utils.neutron-base:/bin/sh: 1: [[: not found
INFO:kolla.common.utils.neutron-base:/bin/sh: 1: [[: not found
INFO:kolla.common.utils.neutron-base:/bin/sh: 1: [[: not found
INFO:kolla.common.utils.neutron-base:/bin/sh: 1: [[: not found
INFO:kolla.common.utils.neutron-base:/bin/sh: 1: [[: not found
INFO:kolla.common.utils.neutron-base:
(cherry picked from commit 441064147a)