Allowerasing (#181)

* Allow erasing during the distro-sync

This is mainly for Oracle Linux but it  will allow a lot more distro-syncs to be
successful instead of crapping out with the migration half done.

migrate2rocky/migrate2rocky9.sh

@@ -1100,7 +1100,8 @@ EOF
     fi
 
     infomsg $'\nSyncing packages\n\n'
-    dnf -y distro-sync || exit_message "Error during distro-sync."
+    dnf -y --allowerasing distro-sync ||
+        exit_message "Error during distro-sync."
 
     # Disable Stream repos.
     if (( ${#installed_sys_stream_repos_pkgs[@]} ||