
This change uses a common DHCPAgentContext and takes care to check for a pre-existing setting in the dhcp_agent.ini. Only allowing a config change if there is no pre-existing setting. Please review and merge charm-helpers PR: https://github.com/juju/charm-helpers/pull/422 Partial-Bug: #1831935 func-test-pr: https://github.com/openstack-charmers/zaza-openstack-tests/pull/157 Change-Id: Ia01c637b0837a4e594d16f6565c605460ad3f922