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Do you still have some critical missing functionality in DNF? And let
us know reasons why would you like to keep YUM available (hopefully
there are no)!
I've not tried 'dnf remove --duplicates' yet, but if it behaves
similar to 'dnf remove --assumeno $(dnf -C repoquery --duplicated
--latest-limit -1 -q)', then there is still no 'sane' way to remove
duplicated packages, which might be needed if 'dnf upgrade' is
terminated half-way. There is also a RFE at [1] for such scenarios,
but it would be enough is 'dnf remove --duplicates' doesn't try to
remove other packages as dependencies of duplicated packages, or
even better, if 'dnf upgrade' is able to 'sanely' continue a
terminated 'dnf upgrade' operation instead of complaining about
conflicts and being unable to proceed. Currently, the user must know
that the problem is duplicated packages, and learn how to safely
remove them without removing other required stuff.