After migration none of my fields are set to required any longer. This patch fixes it, but I think there might be more to this bug- I'm not sure about _content_migrate_get_instance_values - it looks the problem may be just above my patch:
// Pass field settings to the instance, in case they are needed.
$field_value = array(
'require' => $instance_value['required'],
'type' => $instance_value['type'],
'module' => $instance_value['module'],
'settings' => unserialize($instance_value['global_settings']),
i.e., if we're passing field settings to the instance, shouldn't it be $instance_value = array( ... ? $field_value variable seems to be quickly forgotten after this.