Exactly. When it is a small change, just comment it out. But when it’s a large change, create a .old.backup.2013-12-07.dontdelete.

source.php_newnewnew

I wonder how much PHP source code is publically reachable out on the Internet because people would do this without realizing that modphp wouldn't treat it like a PHP file anymore, so an HTTP request to it would cause it to dump the file's source code.

index.php~ for anyone using Emacs