[Aptitude-devel] Dependency resolution

Andrew Davidoff davidoff at qedmf.net
Fri Mar 29 15:50:15 UTC 2013


I'm running into a dependency resolution issue and I am trying to
confirm if there's something I can do to make it go away, or if what
I'm experiencing is just how aptitude is going to work in this case.

I built a Debian package that Pre-Depends on apache2-mpm-prefork, and
Depends on libapache2-mod-python. When I try to install this package,
aptitude complaints as follows:

The following packages have unmet dependencies:
  apache2-mpm-worker: Conflicts: apache2-mpm which is a virtual package.
  apache2-mpm-prefork: Conflicts: apache2-mpm which is a virtual package.
Internal error: found 2 (choice -> promotion) mappings for a single choice.
The following actions will resolve these dependencies:

     Keep the following packages at their current version:
1)     apache2-mpm-worker [Not Installed]

I have dug into the package dependencies and from what I can tell no
packages that are being pulled in as dependencies depend on
apache2-mpm-worker. What I did find was that libapache2-mod-python
depends on apache2, which as I am sure you are aware can be satisfied
by either the prefork or worker variants of apache2. I think this is
where apache2-mpm-worker is coming from.

Barring the possibility that this issue is being caused by something
other than libapache2-mod-python's dependency on apache2, I am curious
why aptitude doesn't run with the selection of apache2-mpm-prefork,
since the package Pre-Depends on it specifically, and it would satisfy
a dependency on apache2?


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