871
xkcd #2897: Light Leap Years
(imgs.xkcd.com)
Alt text:
When Pope Gregory XIII briefly shortened the light-year in 1582, it led to navigational chaos and the loss of several Papal starships.
That is pretty much what I said. I was irritated by your wording "the actual 365.2425", which is just another approximation of the "actual" solar year.
Ah, gotcha, yeah fair enough, I could have said “more accurate”