Replacing an essential package

[Jonathan Nieder <jrnieder@gmail.com>]

Hi APT team,

The xz-utils package in experimental Conflicts/Replaces/Provides the
pseudo-essential package lzma. I think this should be fine, since
installing it only involves overwriting the lzma package rather than
removing it. Indeed, with dpkg or aptitude it installs fine, and
/var/log/dpkg.log does not mention removing lzma. On the other hand,
apt-get decides it needs to remove lzma, resulting in the message

| WARNING: The following essential packages will be removed.
| This should NOT be done unless you know exactly what you are doing!
|   lzma (due to dpkg)

See bug #542060 [1] for the full output. APT bug #169241 [2] also looks related.

Am I misunderstanding policy here? Is apt-get’s behavior useful? If
not, any pointers for one who wants to fix it? In either case, is
there a standard workaround?

Thanks,
Jonathan

[1] <http://bugs.debian.org/542060> “xz-utils - Conflicts with
pseudo-essential package”
[2] <http://bugs.debian.org/169241> “Requires strong confirmation when
replacing an essential package”