Comment 0 for bug 1471287

Race condition hits when creating default security group which results in inconsistency between PLUMgrid controller and neutron and returns this Error:

SecurityGroupExists: SecurityGroupExists: Default security group for Tenant <TENANT-ID> exists.

We need to remove the strict checking of one default security group per tenant in the plugin and allow rollback in case of any failure on the PLUMgrid controller side to take care of the inconsistency.