[tbicr]

I found only two caveats:

- it doesn't use transactions, so if migration will down, then you will need to fix state manually (one point of improvement), however you cannot run `CREATE INDEX CONCURRENTLY` in transaction.

- it can use `CHECK (column IS NOT NULL)` constraint for safe `NOT NULL` replacement for huge tables, that isn't compatible with standard django behavior.

So all this cases highlighted in README.