perl -v gives me

This is perl, version 5.005_02 built for i586-linux
[download]

and running your code produces the following (expected) results :

$VAR1 = [
          undef,
          undef,
          undef,
          undef,
          undef,
          undef,
          undef,
          undef,
          undef,
          undef,
          'foo bar'
        ];
$VAR1 = [
          undef,
          undef,
          undef,
          undef,
          undef,
          undef,
          undef,
          undef,
          undef,
          undef,
          'foo bar'
        ];
[download]

So it's something they broke between 5.005_02 and 5.005_3. Weird.