yarn config set does not allow to set boolean false

[NicBright]

Do you want to request a feature or report a bug?
Bug

What is the current behavior?
yarn config set strict-ssl false sets it to string 'false' instead of boolean false. In consequence, 'false' seems to be treated as truthy and has no effect.

If the current behavior is a bug, please provide the steps to reproduce.
see http://stackoverflow.com/questions/41439008/how-do-you-set-boolean-values-with-yarn-config

Expected behaviour
The config value should have been set to boolean false.

[iredchuk]

OK, this also seems like a duplicate of #1237. But that one is closed already, only the discussion is still going.