redo is not done in a single transaction

[ocadoret]

The redo action does not execute all migrations in a single transaction like the up and down actions. It perfoms the migrations with 2 separated transactions :

• one transaction for the down migrations
• one transaction for the up migrations

So, if an error occurs while performing the "up" migrations, the "down" migrations are committed, without a message indicating that. So if you try to execute again the redo, it will migrate down more migrations before migrating up.

redo action should have the same behaviour as the up and down actions, any errors should also rollback the "down" migrations when an error occurs in the "up" migrations, and leave the database untouched.