785016eb74
With the addition of support to multiple subnets per AZ, backend_details structure was changed in Dummy driver to store multiple subnet primary and secondary public ips in a subnet_allocations list dumped to a json string, breaking upgrading environments that already contains pre-existent share servers in old format. This change fixes the issue by checking if subnet_allocations does exist, otherwise ensure backward compatibility by reading public ips information in the old format. Change-Id: I547de2f4cd82744ecc1cc8180f8cefdf5ec485b4