Bug#689508: ignore obsolete conffiles which are not owned by the package

[Andreas Beckmann]

On 2017-04-21 02:20, Andreas Beckmann wrote:
> The attached patch unconditionally excludes all obsolete conffiles.
> Maybe that is not the optimal approach and a new command line option
> should be used instead (and then we could discuss whether obsolete
> conffiles should be ignored by default - I would say yes).

I don't know if this was now caused by my patch or if it happened
before, but I've just seen this error (see #861136 for the piuparts log):

1m58.2s ERROR: FAIL: debsums reports modifications inside the chroot:
  /var/lib/dpkg/info/inn2-lfs.md5sums is empty but shouldn't!

At this point, the package owned
* an obsolete conffile
* a symlink /usr/share/doc/package -> target
* the directories up to /usr/share/doc
* but no regular files


Andreas