Wrong schema settings

$schema['domain_export'] = array(
    'description' => 'Stores canonical machine names for domains.',
    'fields' => array(
      'domain_id' => array('type' => 'serial','not null' => TRUE, 'description' => 'Domain id. Automatic master key.'),
      'machine_name' => array('type' => 'varchar', 'length' => '255', 'not null' => TRUE, 'default' => '', 'description' => 'The machine name for this domain.')),
    'primary key' => array('machine_name'),
    'indexes' => array(
      'domain_id' => array('domain_id')
    ),
  );

adding not null => True 

to domain.install fixes this.

Sorry, i edited the issue, with code tags.
I don't know how to patch. I'll give it a try, but it won't be very fast, cause i still have to learn how to do it