So, the Kilo release notes say:

nova-manage migrate-flavor-data

But nova-manage says:

nova-manage db migrate_flavor_data

But that says:

Missing arguments: max_number

And the help says:

usage: nova-manage db migrate_flavor_data [-h]
  [--max-number <number>]

Which indicates that --max-number is optional, but whatever, so you try:

nova-manage db migrate_flavor_data --max-number 100

And that says:

Missing arguments: max_number

So just for kicks you try:

nova-manage db migrate_flavor_data --max_number 100

And that says:

nova-manage: error: unrecognized arguments: --max_number

So finally you try:

nova-manage db migrate_flavor_data 100

And holy poorly implement client, Batman, it works.