The recent upgrade did not deal with obsolete conffiles properly.
Please use the dpkg-maintscript-helper support provided by dh_installdeb
to remove these obsolete conffiles on upgrade.

https://www.debian.org/doc/debian-policy/ch-files.html#s-config-files
http://manpages.debian.org/man/1/dh_installdeb

This bug report brought to you by adequate:

http://bonedaddy.net/pabs3/log/2013/02/23/inadequate-software/

$ pkg=darcs ; adequate $pkg ; dpkg-query -W -f='${Conffiles}\n' $pkg | grep obsolete
darcs: obsolete-conffile /etc/bash_completion.d/darcs
 /etc/bash_completion.d/darcs 77bbc645550db183fdcb76083cd234ae obsolete