It started to go dark, then it changed it’s mind.
Yep, the game decided it’s the time for 24 hour non stop daytime 
I found this: https://github.com/CleverRaven/Cataclysm-DDA/issues/1381?source=cc
I am wondering how often does the nightly build get updated on the main page since this had been closed 2 days ago.
The nightly build updates at around 5 am (I think EST, but I’m not sure). I do remember hearing about a problem a few days ago where they realized the nightly build code was still pointing at the old git repository (instead of the new one), but if that’s fixed then it should have updated/will update soon.