AFAICT the code should merge the 10texlive-base.cnfpre-edit into 10texlive-base.cnf (the code to delete 10texlive-base.cnfpre-edit is missing AFAICT), but the merge code doesn't work either.
NO NO NO!!! It should NOT merge the .cnfpre-edit!! It should not create it at all when updating from an old version! If you already have the .cnfpre-edit nothing will change!!! It means, if there is a 10texlive-base.cnf, and it contains # The following added lines have been transferred from # /etc\/texmf\/fmt.d\/10texlive-base-bin.cnf ... ... and removes these lines! Currently, even if these lines are not present, the cnfpre-edit is created. The only change is that if the lines are not present now the package should NOT create the cnfpre-edit file! Best Norbert