With the recent introduction of StorageValue::translate a new pattern appeared in on_initialize:

fn on_initialize() {
    if new_runtime.get() == true {
        MyStorageValue::translate(...);
        new_runtime.put(false);
    }
}

The error proneness is that on_initialize are executed in the order declaration in construct_runtime. Thus if one upper module in on_initialize call your module and use this storage, then the value is still the old encoded one. And thus can leads to very error.

To solve this we can introduce a new function: on_runtime_upgrade_initialize which will be call before all on_initialize.
With this the code to check is just the code contained in on_runtime_upgrade_initialize of other module which logic is easier to audit.

cc @shawntabrizi