./t/050_metaclasses/019_create_anon_with_required_attr.t has an
undef warning without this
# we don't want to clean out the namespace now. We can detect
# that because Moose will explicitly update the singleton
# cache in Class::MOP.
+ no warnings 'uninitialized';
my $current_meta = Class::MOP::get_metaclass_by_name($name);
return if $current_meta ne $self;