Making synaptic and update manager ignore a broken package?

[Adam Funk]

I knowingly installed the Gutsty leafnode package on my system without
meeting the dependency

   dpkg -i --ignore-depends=libc6 leafnode_1.11.6-3ubuntu1_i386.deb

to see if it would work.  (The package says it depends on libc6 >=
2.5-0ubuntu1 but I have 2.5-0ubuntu14 installed.)

Leafnode runs fine but now my update manager and synaptic say they
won't work until I fix the broken package --- by which they mean
uninstall it.

How can I force them to ignore this?


[I've also posted this to the UK Ubuntu-users' list.  Sorry for the
duplication.]

Thanks,
Adam