If an app decide for some reason to attach namespace on the
subscriber before the minitest hook is triggered, we don't want to
reattach the same namespace on the subscriber again. Otherwise each
deprecations would trigger two warnings.
In #26, I made this change but this causes issue if a gem want to
attach multiple namespace to the subscriber.
Only the first namespace will be attached.
If an app decide for some reason to attach namespace on the subscriber before the minitest hook is triggered, we don't want to reattach the same namespace on the subscriber again. Otherwise each deprecations would trigger two warnings.
In #26, I made this change but this causes issue if a gem want to attach multiple namespace to the subscriber. Only the first namespace will be attached.