To reply to myself it seems that I have two solutions:

• Use CGI::Application::Plugin::Redirect
• Update my code:

sub redirectURL
{
    my ( $self, $url ) = (@_);
    $self->header_type('redirect');
    $self->header_add( -url => $url ,
                       -status => 301 );
    return;
}
[download]

That redundent "return" seems to make things work properly in my demo and real application.

I guess the return value of "header_add" is causing problems ..