This is the leaking to which I was refering:

$Foo::var = 'foo!';
$Bar::var = 'bar!';
package Foo;
our $var;
package Bar;
print("$var\n");  # foo!
[download]

$Foo::var = 'foo!';
$Bar::var = 'bar!';
{
   package Foo;
   our $var;
}
{
   package Bar;
   print("$var\n");  # bar!
}
[download]