Newsflash: Source Code Control Systems will KEEP TRACK OF YOUR CODE CHANGES

As Eric Kepes points out here

This means there is absolutely NO need whatsoever to check in code with large blocks of code commented out. I think “change-log” style comments that appear at the top of code files are also un-necessary for this reason. Tracking who changed what and when is the job of source code control systems, not crufty code-comments.