Comment 12 for bug 1040213

The call to crontab -l fails if there is no crontab. Without this check, wakeup fails to set any alarms when no crontab yet exists. The second call is NOT meant to be "-l", it is good as is. This just creates a new crontab when none exists.

That is, if `crontab -l` fails, there is no cron set up, and so we call `echo "" | crontab -`, which creates a new empty cron file.