Setting the system clock backwards causes rsyslog-3.18.1-1.fc9 to stop writing log messages until the clock reaches the former time.  This is a regression from sysklogd-1.4.1-41.fc6.

To reproduce this issue:

1. Disable ntpd
2. Run 'tailf /var/log/messages' in a shell
3. In another shell, run 'logger hello1' to verify that rsyslog is working
4. Run 'date -s 1 hour ago' to roll the clock back 1 hour
5. Run 'logger hello2' and notice that nothing appears in /var/log/messages
6. Run 'date -s 1 hour' to roll the clock forward 1 hour
7. Run 'logger hello3' to verify that rsyslog is working again