Re: Bug#542060: Replacing an essential package
On 2009-08-17 22:07 +0200, Jonathan Nieder wrote:
> 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?
I think it is correct. Since dpkg Pre-Depends on lzma, removing lzma in
favor of xz-utils could theoretically hose your system (imagine that all
Debian packages or even just lzma and xz-utils were lzma-compressed; you
would not be able to unpack them).
> If not, any pointers for one who wants to fix it? In either case, is
> there a standard workaround?
Remove the "Conflicts: lzma" and install a dummy transitional lzma
package that Pre-Depends on xz-utils. This solution should probably
only be implemented when xz-utils is uploaded to unstable, because
downgrading lzma and uninstalling xz-utils will break.
Sven
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