Bug#888850: systemd-timesyncd fails to start

[John Williams]

Package: systemd
Version: 236-6

After a recent installation of buster (aarch64), systemd-timesyncd fails to start 

systemctl status systemd-timesyncd says:
  systemd-timesyncd.service: Start request repeated too quickly
  systemd-timesyncd.service: Failed with result 'exit-code'

I notice that /lib/systemd/system/systemd-timesyncd.service contains both the lines:
  DynamicUser=yes
and
  User=systemd-timesync
but there is no such user as 'systemd-timesync' in /etc/passwd; if I add such a user, the service starts up correctly, running as that user.