If there's unmanaged host with interface that has IP set to it's primary interface but is not marked as primary the migration ends up in invalid state because db/migrate/20140910153654_move_host_nics_to_interfaces.rb creates new interface (skipping validations) with this IP and marks it primary. Then second migration - 20150508124600_copy_unmanaged_hosts_to_interfaces.rb - runs but here it finds the existing one from previous migration and tries to set it's hostname and save it. Unfortunately it's not FakeNic instance so it runs validations and fails on IP uniqueness validation. We can either try to skip saving of interface if it didn't change or improve detection of existing primary interface (probably in both migrations). Setting as release 1.8.2, all users with unmanaged hosts with interfaces created by puppet will hit this.

Migration error that pops up

==  CopyUnmanagedHostsToInterfaces: migrating =================================
-- Migrating Unmanaged Host interfaces to standalone Interfaces
rake aborted!
An error has occurred, all later migrations canceled:

Validation failed: IP address has already been taken