Description of problem:
Happend on locked machine over night, so not really sure what happened, but systemd-logind crashed the same night, taking the logged-in session with it.

Version-Release number of selected component:
systemd-container-239-11.git4dc7dce.fc29

Additional info:
reporter:       libreport-2.10.0
backtrace_rating: 4
cmdline:        /usr/lib/systemd/systemd-machined
crash_function: clock_boottime_supported
executable:     /usr/lib/systemd/systemd-machined
journald_cursor: s=583d50c7c1df4d4585d17d052917b6ca;i=45bb;b=07fa6cc498324f10a19a710b06d6eb5b;m=315172eb3b;t=581ced3927c8a;x=6767208f0b320f9c
kernel:         4.20.6-200.fc29.x86_64
rootdir:        /
runlevel:       N 5
type:           CCpp
uid:            0

Truncated backtrace:
Thread no. 1 (6 frames)
 #0 clock_boottime_supported at ../src/basic/time-util.c:1347
 #1 triple_timestamp_get at ../src/basic/time-util.c:80
 #2 sd_event_wait at ../src/libsystemd/sd-event/sd-event.c:3412
 #3 sd_event_run at ../src/libsystemd/sd-event/sd-event.c:3566
 #4 bus_event_loop_with_idle at ../src/shared/bus-util.c:119
 #5 manager_run at ../src/machine/machined.c:390

Potential duplicate: bug 1412612