Guarantee each() iterates through the entire hash.

[schwern]

The major problem with each() is it is vulnerable to this subtle bug...

while( my($k,$v) = each %hash ) {
    ... do something ...
    last if $k eq "Foo";
}

This leaves the iterator of %hash incomplete. The next loop will not iterate through the complete hash. This makes each dangerous to use.

autobox::Core can solve this by resetting the iterator.