sidux/aptosid does/did custom kernels based on the latest (unlike vanilla debian sid) so on account of that they had to also put patches onto a bunch of other stuff and sometimes (/frequently) their repos got out of sync. You can read all about it
here if you are so inclined.
It did put me off the whole rolling release idea, and now I just clean install fedora, ubuntu and opensuse every year or two depending on when support runs out, the hdd dies, or I want to see some new thing. I generally run updates monthly, mainly for the security fixes (but not excluding others).