Subject: Bug#216768: apt: Confirmed under Lenny with several sources and pinning

From: "Jesús M. Navarro" <[email-masked]>
Date: Mon, 2 Nov 2009 21:32:34 +0100

Hi, David:

On Monday 02 November 2009 16:40:00 David Kalnischkies wrote:
> Hi all,

[...]

>
> The "real" bug here showed by diff (and a few other before)
> is therefore something like this:
> New essential package A replaces old essential package B.
> (Package B is now a transitional package to A.)
> The user (with mixed sources) tries to deinstall package B and
> apt refuses that as it thinks B is essential - it doesn't take into
> account that A provides the same functionality as B.
>
> Could we agree on that it is a (very) minor bug?

No.  At least not a package bug.  Your very reasonement about why all 
essential packages are tried to be installed works here too: you have 
packages from versions N and N+1 where packages on N depend on 
essential "foo" and those on N+1 depend on the new essential "bar" which 
overrides "foo".  Then you can't gratuitously assume that even if "bar" is 
functionally-wise the same as "foo" versions on N will in fact be able to 
work with "bar": you don't know how many or how deep changes where needed on 
N versions to make them work nicely with "bar" as they go N+1 (which it's, in 
fact, the main function of the very distribution effort: manage to get a 
disparaged bunch of packages to smoothly work together).

So I don't think that's a bug but an unsupported corner-case.