wp_schedule_single_event() weirdness

[scribu]

I've written this test plugin: ​http://wordpress.pastebin.ca/1298571

If I set it to a time in the past, like

wp_schedule_single_event(time(), CRON_HOOK);

it fires twice on every page load.

If I set it in the future, say

wp_schedule_single_event(time()+10, CRON_HOOK);

it fires once, or not at all, even if I clear the hook first.

Tested on:
WP 2.7.1-alpha-10188 on localhost (Ubuntu 8.10 + LAMP, PHP5).
WP 2.7 stable on live server (Linux, PHP5)

[ryan]

​http://comox.textdrive.com/pipermail/wp-testers/2009-January/011017.html