Should @x be defined after only "my @x"? (RT #64968)

[Kyle Hasselbacher]

use v6;

my $s;   #  ! $x.defined
my @a;  # @a.defined

That's the current Rakudo behavior.  RT #64968 suggests that this is a
bug.  In Perl 5, @a would not be defined until something was put into
it.  Which should it be?  I'd like to write a test for this.

Thanks.

Kyle.