In the method scheduler.run in the sched module, heapq.heappush is
called with single argument (event).  It's a two argument function.  The
correct call would be heapq.heappush(q, event).

This problem is probably not frequently experienced because it only
occurs if the delay function modifies the queue, deleting the top entry
while sched.run() is waiting to execute it.

A patch is attached based on the trunk.