Comment 4 for bug 684244

> > 3. I don't see any locking around the updates of /var/run/motd.new, so it seems that multiple parallel logins could easily case corruption

> Confirmed, that appears to be a bug. Patches welcome of course. It's not the highest priority for fixing, given that a corrupted motd isn't particularly fatal.

Speaking of "patches welcome", I provided a bzr branch for a similar motd corruption caused by a different script in https://bugs.launchpad.net/ubuntu/+source/update-notifier/+bug/1146170 seven months ago. As of today, nobody responded.