bug#65306: [shepherd] ntpd throws shepherd out of the loop

[Liliana Marie Prikler]

Hi Guix,

I have a laptop that's a little stuck in the past… more accurately
January of 2020 thanks to what I believe to be an empty CMOS battery. 
As of recently (maybe it dates back longer, but I first experienced it
two weeks ago and just now got to debugging it a little), Shepherd gets
stuck at 100% CPU usage "early" on first boot.  I can prevent this
issue by getting the system time "close enough" to the actual time
before the NTP sync, but see the first sentence.  Not having a network
connection also works, but that's somewhat unpractical.  Also, the high
CPU usage still occurs if a sync is done later.  I have yet to
encounter the bug post hibernation, but I also wish not to.  There
doesn't appear to be anything particular interesting in the logs
either.

Cheers