I was dev lead for the Microsoft C runtimes (msvcrt.dll and the like) back around the turn of the century. We shipped most of the source for the runtimes with Visual C++, and included a copyright message in each file. Those had the copyright year range in them when I started in the position, but (IIRC) we got the all-clear to dump the years from the text, over 20 years ago. Certainly cut down on source churn at the start of each year.
So many programmers cargo cult on updating the copyright years every year, as if they would magically lose their legal rights on January 1. They just follow the crowd with ignorance of the law and irrational fear. Show me one case in the history of law where someone has lost their copyright by not bumping the year on the notice. Kudos to Stenberg for ending this pointless ritual.