Dear Konrad, Due #1041332, I reopened this bug some days ago.
The Debian Policy[1], in its clause 10.7.3, doesn't allow the install system to modify (moving) configuration files. IMO, the best way for MRTG is to show a message to users asking for a manual action. I will do an upload to provide it soon (tomorrow?). This upload will close this bug. Sorry for this solution and feel free to reopen if needed (but if this bug be reopened, I will set a tag wontfix for it). Thanks a lot for your attention. [1] https://www.debian.org/doc/debian-policy/ch-files.html#behavior Regards, Eriberto
