If you ever find yourself running into a monotonous
"The following packages have been kept back"
error message when you run
sudo apt-get upgrade, then the "fix" is to either run
apt-get dist-upgrade which is quicker, but sounds more ... dangerous or to run
apt-get install [package list] where package list is a list of all packages that have been kept back.
How this is not considered a bug, I have no idea. Apparently, the package in question depends on a new package which has not yet been installed and the dist-upgrade apparently looks and suggests, while plain upgrade does not.
I wonder how adept and synaptic handle this situation behind the scenes.