I'm not sure if you're joking. Ruby on Rails projects aren't the only ones that have files that shouldn't be made public on GitHub.

GitHub will already generate a .gitignore file when you create a repository on its website. It would be nice if the .gitignore file was based on the type of project being created. And it would be nice if it gave a warning when files that are in the default .gitignore were being pushed to the repo.

If the filename changes in the future, who cares? It defaults to the current situation where no warning is given, but potentially improves security in many cases. And it's not a big deal to add another file to a list.