Expire menus incompatible with Panelizer

When Expire menus is enabled and a Panelized node is saved it causes the menu link to be deleted. This is due to menu_node_prepare being called which adds the $node->menu item to the node but doesn't set $node->menu['enabled'] to TRUE so when Panelizer triggers the node_save after this menu_node_save deletes the menu link. I'm not sure if we can just set the $menu_node->menu['enabled'] = TRUE in expire.module or whether that will have unintended consequences when a user intends to remove the menu link. Attached is a patch that adds that -- stolen liberally from Feeds -- but I confess I haven't tested it to see whether it functions as desired.