The symlink creates what is effectively a version-controlled gitignore. It would be the obvious way of getting around your arbitrary restriction (and how do you know they are not doing this, the symlink is not checked in).

My comment and the other replies show you how to use git to check and clean the files of the much maligned horked build script. These will work regardless of the gitignore contents.

But then again, pretty sure you are just having a laugh at our expense by taking this ridiculous position.