WordPress at a glance
action is not described

_core_updated_successfully action-hook . WP 3.3.0

Fires after WordPress core has been successfully updated.

Usage

add_action( '_core_updated_successfully', 'action_function_name_5962' );
function action_function_name_5962( $wp_version ){
	// action...
}
$wp_version(string)
The current WordPress version.

Where the hook is called

update_core()
wp-admin/includes/update-core.php 1198
do_action( '_core_updated_successfully', $wp_version );

Where the hook is used (in WP core)

wp-admin/includes/admin-filters.php 131
add_action( '_core_updated_successfully', '_redirect_to_about_wordpress' );