Were you running without rebooting with an older version of systemd than 219-4ubuntu3? This one contains the upstream commit 6487ada88d63e4998113f4c57fa10b7c865f8026, which was supposed to fix that.
Putting as incomplete as long as you can't reproduce with latest version.
Were you running without rebooting with an older version of systemd than 219-4ubuntu3? This one contains the upstream commit 6487ada88d63e49 98113f4c57fa10b 7c865f8026, which was supposed to fix that.
Putting as incomplete as long as you can't reproduce with latest version.