Holger Levsen: > Process: 375 ExecStart=/usr/sbin/haveged --Foreground --verbose=1 > $DAEMON_ARGS (code=exited, status=226/NAMESPACE)
226/NAMESPACE suggests it's a problem with the hardening we do in the systemd unit file. Please try disabling all such hardening, and if it fixes stuff, re-enable them one after the other to isolate the culprit. Thanks! Now, it looks like it might be a different bug than the one filed by Vagrant (his only happens with Linux 4.12).
