After reading through the last pages I'm sure of 2 things:
- Some beta tester thought it would be fun to leak such an update without even an exe file on April 1st.
- The mods are in on it and contributed to this mistake in good faith.
I don't think the dev team knew anything about this because it indeed may make a bad impression on those downloading it for the first time. This could turn away potential new players unaware of what day it is.
But I also believe it was just a genuine mistake from some beta tester who didn't want to harm the devs, but just thought it would be a funny joke.
In any case, it's a bit sad that someone could be such a fool on April fool's