4.0's upsert doesn't work with 1, only with true

I’m using node.js driver, version 4.0.x and this options here:
https://mongodb.github.io/node-mongodb-native/4.0/interfaces/updateoptions.html#upsert

Only works if you use “true”, with 1 it is ignore. Not only the use of digits instead of boolean values is widely accepted in the driver, but it used to work on past versions.