Small update with system enhancements, still based on Android 4.1.2
HTC One phones that were sold unlocked via HTC, including the developer editions, in the U.S.A. are getting a small over-the-air update today. As you can see it's a 17MB file containing "important enhancements and bug fixes". Without seeing the actual change log, we're going to guess this is an update you'll probably want to take.
When all said and done, you're at Software Number 1.29.1540.16, Android version 4.1.2 and HTC Sense 5.0. The usual warnings about root and custom recovery apply, so be sure to have that RUU handy, or wait for a flashable version.