antirez/redis — pull request #647 by jokea (2012-08-29 02:27:01+00:00)
Title: Fix for issue #633

When system time changes back, the timer will not worker properly
hence some core functionality of redis will stop working(e.g. replication,
bgsave, etc).

The patch saves the previous time and when a system clock skew is detected,
it will force expire all timers.

This patch also make the timer list in sorted order, so getting the nearest
timer is O(1) now.(Although adding/deleting timers are still O(N)).