L3: Add in missing translation
L3: Add in missing translation

Commit a7c633dc8e8a67e65e558ecbdf9ea8efc5468251 missed
a translation for a exception that is raised.

TrivialFix

Change-Id: Ib47a743ef05a2f9b235daf8d06ecd47d8b840fa0

huntxu/neutron,noironetworks/neutron,openstack/neutron,openstack/neutron,eayunstack/neutron,mahak/neutron,huntxu/neutron,openstack/neutron,eayunstack/neutron,noironetworks/neutron,mahak/neutron,mahak/neutron