mitchellh/vagrant — pull request #3877 by cielavenir (2014-05-22 01:30:44+00:00)
Title: favorite SSH client is not limited to PuTTY

There are SSH alternatives such as Tera Term and MobaXterm as well as PuTTY.

By the way, ssh_is_putty_link is unchanged since (I think) Tera Term and MobaXterm don't have CUI client (plink equivalent).