aptitude safe-upgrade
Erich: I do sometimes wonder why we don’t relax the definition of “safe” upgrades to include installing new packages but still not removing old ones. I know that many of my uses of dist-upgrade are just for when something grows a new dependency that I didn’t previously have installed.
(Of course this wouldn’t always help as it wouldn’t account for a new dependency that conflicted with an old dependency, but never mind. It would certainly do wonders for the metapackage case.)