6.5.1 The dpkg-divert command

File diversions are a way of forcing dpkg not to install a file into its default location, but to a diverted location. Diversions can be used through the Debian package scripts to move a file away when it causes a conflict. System administrators can also use a diversion to override a package's configuration file, or whenever some files (which aren't marked as conffiles) need to be preserved by dpkg, when installing a newer version of a package which contains those files (see Preservation of local configuration, Section 2.2.4).

     # dpkg-divert [--add]  filename # add "diversion"
     # dpkg-divert --remove filename # remove "diversion"

It's usually a good idea not to use dpkg-divert unless it is absolutely necessary.