sinatra/sinatra — pull request #634 by postmodern (2013-02-10 05:42:14+00:00)
Title: Default host to localhost when in development mode.

Running Rack apps on `0.0.0.0` in development mode will allow malicious
users on the local network (ex: Coffee Shop) to abuse or potentially
exploit the app. Safer to default host to `localhost` when in development
mode.