fix write config after setting override map

[WyRainBow]

Fixes config write output when a parent key is overridden with a map via Set().

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}