Bug#689813: libgraphite2-3: misses Breaks: libgraphite2-2.0.0

[Andreas Beckmann <debian@abeckmann.de>]

On 2012-10-06 19:17, Rene Engelhard wrote:

after
  install A
  install B
  remove B

>> That package is now non-functional, so we *need* a Breaks or similar.
> 
> The old package does not need to be functional anymore. libgraphite3-2

A is a crippled package at this point, nobody notices as long as B is
installed.

> contains a symlink for the old SONAME and Provides: libgraphite2-2.0.0 so
> a) the r-deps have their dependency fullfilled and b) the r-deps still work.

But crippled A without B still fulfills the dependencies of the
rdepends. But they don't work. A is now RC because of B.
So the having a crippled A installed must be forbidden by appropriate
relationships.

> And Downgrades (where this would matter that removing libgraphite3-2 leaves
> a non-functional libgraphite2-2.0.0) are not supprted.

That is not a downgrade from dpkg's point of view. Add a Breaks and it
looks a bit more like a downgrade.

Andreas