`module.children` is supposed to be the list of modules included by this
module but lib/module.js failed to update the list when the included
module was retrieved from `Module._cache`.
Fixes: https://github.com/nodejs/node/issues/7131
PR-URL: https://github.com/nodejs/node/pull/14132
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
