Hardy Heron: saving list of installed packages and using for new install

[Bruce Marshall]

On Monday 21 April 2008, p.daniels wrote:
> May I quote this tip on my blog?
>
> best-
> pete
>
> On Sunday 20 April 2008 10:43:07 Ulrich Grün wrote:
> > To make installation of your favoured packages more easy, you could save
> > your list of installed packages from your old system, and then use this
> > list for your new one:
> >
> > dpkg --get-selections > list-of-installed-packages
> >
> > dpkg --set-selections < list-of-installed-packages
> >
> > then with aptitude with option 'g' or with synaptic or other packaging
> > programme: installation of this list of packages. Maybe, an apt-get
> > upgrade will do this as well (not tested)

I've used this approach before with success but now when I try it I get:

"the following will be uninstalled:

apt base-files bash dash 

And that the whole operation is inherently dangerous.

Something must have gone west.   This is taking a list from a gutsy system and 
using the list on hardy.