Bug or feature? Hash autovivification

[Ovid]

Just stumbled across this, but I can't tell from S09 if this is a bug or 
feature:

  $ ./perl6 -e 'my %foo; if %foo<a> {}; say %foo.perl'
  {"a" => undef}

 
I wasn't expecting auto-vivification there.  The examples in S09 use HoH 
instead of a flat hash:

    But these bindings do autovivify:

           my %hash;
           my $val := %hash<foo><bar>;

           my @array;
           my $cap = \...@array[0][0]; # $cap is a Capture object ‐ see S02
           my :($obj) := $cap;   # @array[0][0] created here

           my @array;
           foo(@array[0][0]);
           sub foo ($obj is rw) {...}  # same thing, basically

           my %hash;
           %hash<foo><bar> = "foo"; # duh

So is this a bug?

Revision: 34706

$ uname -a
Darwin curtis-poes-computer-3.local 9.5.1 Darwin Kernel Version 9.5.1: Fri Sep 
19 16:19:24 PDT 2008; root:xnu-1228.8.30~1/RELEASE_I386 i386

Cheers,
Ovid
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