capistrano/capistrano — pull request #979 by ArtemPyanykh (2014-03-20 15:57:51+00:00)
Title: Add Configuration#set_default.

It is quite convenient to be able to set default value for some key. It
is possible to use `#fetch(:key, :default)` whenever we need, but `#set_default` seems
more convenient and straightforward.