Next Hook::LexWrap 18

Altering the Return Value: Prewrappers

Instead, the code looks like this:

        $return = bless sub {$prereturn=1}, 'Hook::LexWrap::Cleanup';
        my $dummy = $wrapper{pre}->(@_, $return) if $wrapper{pre};
        unless ($prereturn) {
                $return = &$original;
                $dummy = scalar $wrapper{post}->(@_, $return)
                        if $wrapper{post};
        }
        return $return;

If the prewrapper overwrites $_[-1], this overwrites $return
Since $return is a Hook::LexWrap::Cleanup object, Hook::LexWrap::Cleanup::DESTROY is called

        sub DESTROY { $_[0]->() }

This invokes sub {$prereturn=1}
So the unless block is skipped