The testsuite failure actually comes from this unsetting when a warning occurs (the PackageRepository uses a validating loader).

However, without this change, the testsuite of the ValidatingArrayLoader was failing because there is a test checking that data triggering a warning gets removed before calling the inner loader.

I think removing requirements on warning is probably too intrusive (especially as the ValidatingArrayLoader is not only used in the ``valdiate`` command but also on runtime by repositories). What do you think @Seldaek ?