Comment 49 for bug 294667

> BTW it sucks that update-manager will not take into account the forbid-version from aptitude...

Yep, I had noticed this both for this backports issue, and for another problem with some piece of hardware needing a custom-compiled module (which I don't want overwritten!). Because of this problem I do the updates using apt-get. I've found an associated bug: see bug #210210.