To save others some time investigating why their daily / weekly / monthly cron jobs (those located in /etc/cron.{daily,weekly,monthly}) run twice when transitioning from DST to non-DST, it's a bug in /usr/sbin/run-crons <https://bugs.gentoo.org/69777> (yes, you've read the bug number correctly). The script is too eager to clean up stale "lastrun" files.
I attached a patch to the bug, but considering how old the bug is, and from the tone of the discussion there, I have little hope that it gets applied. If you would like to see this fixed, it may be worth chiming in on the bug. Or if you're a kind Gentoo developer listening to affected users, to take action. -- Remy