Comment 8 for bug 613412

I think the deletion of 20packagekit was just a test Jonathan wanted the original poster to perform in order to confirm where the problem lies, and is not an outright fix.

Upgrading packagekit yesterday showed that the file is still part of the package (and allowing it to put it back showed the same problem still exists).

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Setting up packagekit (0.6.6+20100703a-0ubuntu3) ...

Configuration file `/etc/apt/apt.conf.d/20packagekit'
 ==> Deleted (by you or by a script) since installation.
 ==> Package distributor has shipped an updated version.
   What would you like to do about it ? Your options are:
    Y or I : install the package maintainer's version
    N or O : keep your currently-installed version
      D : show the differences between the versions
      Z : start a shell to examine the situation
 The default action is to keep your current version.
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