passing already installed package to software-center causes conflict message

Thanks for your bugreport.

What package did you experience this problem with? I just checked with the (super simple) 2vcard and there I get a correct "Reinstall" prompt.

It was with this initially

http://synergy.googlecode.com/files/synergy-1.4.3-Linux-x86_64.deb

I also tried with a few random packages from /var/cache/apt and got the same message.

I agree 2vcard does get the correct 'reinstall' prompt but nothing else seems to?

I just tried these following packages from the apt cache, all come up with the conflict message, rather than the reinstall message

gnome-shell
gnome-accessibilty-theme
apport-gtk
zeitgeist-extension-fts

so I believe this problem occurs with any package that has a dependency set to conflict with itself. Which is the vast majority of packages.

for example for gnome-shell, you have

Conflicts: gnome-shell

This is actually a bug in apt.debfile (from python.apt package)

def _check_single_pkg_conflict(self, pkgname, ver, oper):
        """Return True if a pkg conflicts with a real installed/marked pkg."""
        # FIXME: deal with conflicts against its own provides
        # (e.g. Provides: ftp-server, Conflicts: ftp-server)

here is a patch that fixes the bug In python-apt.

I will also re-assign this bug to python-apt, since software-center is just playing the messenger here, and passing on the error message from apt.debfile.

Internally, python-apt uses libapt-pkg, which for each package that has neither "Architecture: all" nor "MultiArch: same" properties generates a synthetic confclit with its own versions for other architectures. I.e. gnome-shell for amd64 conflicts with gnome-shell for i386, and vice versa, which makes sense.

However, python-apt fails to take architecture-specific conflicts (such as gnome-shell for amd64 conflicting with gnome-shell for i386) into account, and instead interprets them as plain conflicts of a package with itself.

I believe the attached python-apt.fix2.patch is a superficial fix that doesn't fix the real problem but happens to fix its symptom. I'll make another fix.

Added a merge request for lp:~feldgendler/python-apt/829138 with my version of a fix.

I was confused by the presence of both lp:python-apt and lp:ubuntu/python-apt and unsure where to request merging of my fix. I chose the latter, was it right?

It looks to me like python-apt is a mirror of Debian's code. You can see this by following the lp:python-apt link above, so ubuntu/python-apt is the right branch.

OK then. I suppose there is a process by which fixes in Ubuntu's mirror are routinely submitted upstream.

This bug was fixed in the package python-apt - 0.8.3ubuntu1

---------------
python-apt (0.8.3ubuntu1) precise; urgency=low

  * merged from debian/sid

python-apt (0.8.3) unstable; urgency=low

  [ Alexey Feldgendler ]
  * handle architecture-specific conflicts correctly (LP: #829138)

  [ Michael Vogt ]
  * lp:~mvo/python-apt/debfile-multiarch:
    - add multiarch support to the debfile.py code (LP: #854839)
  * tests/test_apt_cache.py:
    - add additional check if provides test can actually be run

python-apt (0.8.2) unstable; urgency=low

  [ Michael Vogt ]
  * merged from ubuntu:
    - use logging instead of print
    - update distro template Ubuntu.info.in
    - add xz compression support
  * po/python-apt.pot:
    - refreshed
  * po/pt_BR.po:
    - updated, thanks to Sergio Cipolla (closes: #628398)
  * po/da.po:
    - updated, thanks to Joe Dalton (closes: #631309)
  * po/sr.po:
    - updated, thanks to Nikola Nenadic (closes: #638308)
  * python/apt_pkgmodule.cc:
    - add apt_pkg.get_architectures() call
  * apt/cache.py:
    - remove "print" when creating dirs in apt.Cache(rootdir=dir),
      thanks to Martin Pitt
    - add __lt__ to apt.Package so that sort() sorts by name
      on list of package objects
  * debian/control:
    - add recommends to xz-lzma to ensure we have the unlzma command
  * apt/cache.py:
    - set Dir::bin::dpkg if a alternate rootdir is given
      (LP: #885895)
  * build fixes for the apt in experimental
  * apt/debfile.py:
    - raise error when accessing require_changes and
      missing_deps without calling check() before, thanks to
      Tshepang Lekhonkhobe (closes: #624379)
  * apt/package.py:
    - add new "suggests" property, thanks to Christop Groth
    - allow Dependency object to be iteratable, this allows to write
      code like:
      for or_dep_group in pkg.candidate.dependencies:
          for dep in or_dep_group:
              do_something()
      (thanks to Christop Groth)
  * apt/progress/base.py:
    - write exception text to stderr to avoid hidding exceptions
      like "pre-configure failed" from libapt (thanks to Jean-Baptiste
      Lallement)

  [ Tshepang Lekhonkhobe ]
  * rm usage of camelcase in cache.py doc (closes: #626617)
  * grammar fix in the cache.py doc (closes: #626610)

  [ Nikola Pavlović ]
  * fixed a typo, changed "Open Source software" to
    "free and open-source software" (LP: #500940)
 -- Michael Vogt <email address hidden> Thu, 08 Dec 2011 20:44:30 +0100