Callbacks due to :dependent options have potentially unintended effect

[mvz]

The dependent option for has_many creates a callback that is executed on soft-deletion. However, it may make more sense to execute it on hard-deletion, because otherwise the deletion cannot be undone (unless the action is destroy and the relation is also paranoid).

Options:

• Move some of these callbacks to the hard-delete stage
• Warn about these callbacks (i.e., make people not use them)