both 'use base' and @ISA appear in auto generated Manager classes

Auto-generated Manager classes have both a 'use base' statement and an
@ISA declaration.
--------------
package LGG::DB::Booking::Manager;

use base qw(Rose::DB::Object::Manager);   # <---- should be sufficient

use LGG::DB::Booking;

our @ISA = qw(Rose::DB::Object::Manager); # <---- superfluous

sub object_class { 'LGG::DB::Booking' }

__PACKAGE__->make_manager_methods('bookings');

1;
--------------

Also, a feature request.  Would it be possible to provide a custom
base class for these auto-generated Manager classes? You can already
provide a 'base_class' for your object classes, but I would like to
have a 'manager_base_class' option if possible.  I have some methods
that I want to add to all Manager classes.

Cheers,

Cees