Dear Ian, Christian, flash-kernel has been blocked from entering testing for long time. The QA page [0] says it's because serious bugs, which I think there's only #813995 on the list. #813995 affects since 3.35+deb8u2, which is in stable [1].
Simply speaking, there's no critical issue for the package in sid. For such case, I suggest you release the blocking manually. Thank you! [0]: https://qa.debian.org/excuses.php?package=flash-kernel [1]: https://tracker.debian.org/pkg/flash-kernel Cheers, -- Roger Shimizu, GMT +9 Tokyo PGP/GPG: 17B3ACB1