Add an option for "overwrite" field values

I'm using 5.x-dev17

I've tried to import an update for a taxonomy that has existing field values.
Currently under "the question "What will existing term become when a term with same name and same language will be imported?" I have two options - Update/merge fields OR Ignore/create new

It would be really useful if there was a third option. Update and overwrite field values.
I tried importing an existing taxonomy exported as Fields by the CSV Export feature, though the altered values were just ignored when I chose to merge. It seems your logic assumes that I want to keep any data currently in taxonomy fields, and there's no way for me to update existing values, I'm only able to provide values for empty fields when I import.

This feature request is useful, since it allows for a batch update of taxonomy fields while keeping the existing tid's.